This is the world's first ever actual pool of Jello. And while it may look simple, it's actually a very difficult engineering challenge to pull off. As proof, if you Google Jello pool, you will either find bad CGI or a handful of videos of people who tried to do this, but it really didn't work out. So today, we're going to answer possibly the longest standing question from my childhood, what would it be like to actually belly flop in a pool of Jello. But before we do that, I want to talk about what we actually had to go through for the past six months to pull this off. The idea of a Jello pool has been on my bucket list for over four years. In fact, when Kevin from The Backyard Scientist and I made the 25 million Orbeez pool, our first idea was to do a pool of Jello, but it's really hard because if you've ever made Jello, you might recall you first have to boil water, then mix in the powder, and then you have to refrigerate it for it to actually get firm. And that's easy enough to do for a small dish, but how do you boil and then refrigerate an entire pool? This seemed like a very worthy engineering challenge. So last year Thanksgiving, my brother and I came up with a plan, and then in the middle of winter, we started digging a hole in his backyard. Then over the course of two months, we set up a bunch of small scale experiments because we needed to answer questions like how much gelatin powder does it actually take to get to the ideal firmness and how hot and then cold does the mixture actually need to get for the Jello chemical reaction to take place so it will actually get firm. From our experiments, we learned the Jello always got firm as long as the mixture got hotter than 160 degrees Fahrenheit. So we decided we could scale this up by using six 55 gallon drums with a custom propane burner underneath and a spigot we welded to the side, but more on that later. So now we knew how we were going to heat it up, but how do you refrigerate an entire pool? For that, we teamed up with Mother Nature and just picked the perfect location and time of year. We installed a thermometer and starting in January, we tracked the temperature in his backyard every night. We needed refrigerator temperatures at night, but not freezer temperatures because that would freeze the Jello and our experiments showed that totally ruins it. And so after looking at our data plus historical temperature plots, we knew we had about a three week sweet spot window towards the end of April to pull this off. Our goal was to have a Jello pool party in his backyard that would make even Phineas and Ferb jealous. So the plan was to start seven days before the party and fill the pool with an average of 10 barrels every day. That would give each layer a chance to get exposed to the cold night air to more efficiently get rid of the heat. And so with that, first thing Saturday, a full week before the party, we got to work. We didn't want to waste actual food. So this is just water and gelatin powder and food coloring, but there's no sugar. We intentionally placed our barrels much higher than the pool. So when we were ready, we could use the potential energy to move the Jello from the barrels to the pool. We had to tackle about a thousand other issues that came up that I won't bore you with, but day by day and layer by layer, the pool began to fill up. Because the Jello went in with so much heat energy we needed to remove before it could get firm, in addition to using the cold night air, my brother's neighbor Nick happened to have a spare swamp cooler in his shop. So we kept that running over the top of the pool pretty much the whole week. This gave us convection cooling. It's the equivalent of rolling down a car window for the pool or like when you blow on the top of a hot cup of soup. This constantly replaces the boundary layer of air right at the surface with fresh, cold air that will suck out the heat more efficiently. And so, as we put in the final batch Friday night with ominous weather threatening to ruin the whole effort, at this point, we had done all we could. We were exhausted after a week and I wasn't feeling super confident because my specialty is more with mechanical things and this project was more about chemistry and thermodynamics. And I didn't want that lame Gelli Baff stuff people try and pass off as Jello. And so even if it didn't last long in the sun, I wanted to at least have the experience of seeing even a single belly flop on a smooth pool of actual Jello. If this was going to be a total failure, it wouldn't be from lack of effort. And so we woke up Saturday morning with a forecast for a warm, sunny day and we pulled off the tarp to find a pool filled with actual freaking Jello. By this point, word in the neighborhood had definitely spread around as to what we were up to. And my brother asked if some of their friends' kids could have first dibs. And so with that, I'm happy to report this is what it looks like to belly flop in a pool of Jello. Not yet. Careful. When I first got in myself, it was closer to the middle of the day. And one of the things we discovered was that direct sunlight over time had the effect of undoing some of the solidness of the lower layers. When you go in, it just like fills your nose and like ears. It's a very surreal feeling of just being like, it's kind of hard to move, but it's just slimy and slippery. It actually feels really cool. We have some pool toys uh hidden underneath. Got it. Wow. Unlike anything. I mean it's like swimming in snot if that makes any sense. But like a good snot. To keep it solid for even longer, if we were to do it again, we might put in a heat exchanger pipe system beneath the surface, sort of like how they freeze indoor ice skating rinks. And maybe use a little sugar. That's disgusting. Now at this point, you might be thinking, why would anyone spend the effort of six months of planning and then a solid week of backbreaking effort just to make a stupid pool of Jello? And to that I say, why do people go through the effort of climbing Mount Everest? Why did Neil Armstrong go through the effort of stepping on the moon? And why did Pam and Jim go through the effort of convincing Dwight that Jim had always been Asian? This is Jim. Sometimes you don't do a thing because you should, but simply to prove that you can. Now that my curiosity was fully satiated and in my ongoing quest to be the favorite uncle, I told my nephews they could invite some of their friends over and my brother's family set up a neighborhood barbecue. And at this point, after a lot of hours of belly flops and bowling balls and direct sunlight, the Jello was pretty broken down, but that didn't stop us from setting up a Jello pool slip and slide. And everybody starts to move. As soon as... And I loved their sense of adventure, but it was a bit of an uncle fail moment because apparently none of them have ever used a slip and slide. We didn't actually put any sugar in here, so it's kind of just disgusting. So we've got some real jello.
A man stands waist-deep in a large, rectangular pool filled with vibrant red Jell-O, gesturing with his hands towards the Jell-O.
"This is the world's first ever actual pool of Jello."
Setting: suburban backyard — bright, natural daylight
People (1):
• standing in the Jell-O, waist-deep, wearing black short-sleeve athletic shirt and not visible, short brown hair — smiling, speaking enthusiastically
The man in the Jell-O pool raises his right index finger to emphasize his point, looking directly at the camera.
"And while it may look simple, it's actually a very difficult engineering challenge to pull off."
Setting: suburban backyard — bright, natural daylight
People (1):
• standing in the Jell-O, waist-deep, wearing black short-sleeve athletic shirt and not visible, short brown hair — serious, explanatory expression
A montage of clips showing failed or fake Jell-O pools: a CGI commercial, a man diving into a watery red substance in an inflatable pool, and another man looking disappointed in a similar pool.
"you will either find bad CGI or a handful of videos of people who tried to do this, but it really didn't work out."
Setting: various backyards — varied, mostly daylight
People (1):
• sitting or falling into inflatable pools, wearing shirtless and swim trunks, varied hair — varied, from excited to disappointed
Text: "youtube/unspeakable", "youtube/Joy Jefferson"
A slow-motion shot of a young boy belly-flopping onto the surface of the red Jell-O pool. The Jell-O ripples and gives way slowly under his impact.
"what would it be like to actually belly flop in a pool of Jello."
Setting: suburban backyard — bright sunlight
People (1):
• horizontal, mid-belly-flop, wearing dark t-shirt and black shorts, short brown hair — concentrated
The man stands in a workshop, speaking to the camera with his hands clasped in front of him.
"The idea of a Jello pool has been on my bucket list for over four years."
Setting: workshop — bright, even indoor lighting
People (1):
• standing behind a workbench, wearing black t-shirt with a graphic print and gray jeans, short, dark, styled hair — smiling, speaking
A montage shows clips of a previous project: a pool filled with millions of colorful Orbeez. People are shown jumping and swimming in the dense balls.
"made the 25 million Orbeez pool, our first idea was to do a pool of Jello, but it's really hard."
Setting: backyard pool — daylight
People (1):
• swimming and playing, wearing shirtless and swim trunks, varied hair — laughing and excited
Text: "youtube/MarkRober"
A sequence of shots demonstrates the small-scale process of making Jell-O: a pot of water boiling on a stove, a packet of Jell-O powder being poured in, and a glass bowl of the mixture being placed in a refrigerator.
"you might recall you first have to boil water, then mix in the powder, and then you have to refrigerate it for it to actually get firm."
Setting: kitchen — indoor kitchen lighting
People (1):
• performing actions, not visible hair — not visible
An animation shows a picture of a backyard pool. A thermometer next to it first turns red and rises (boiling), then turns blue and drops (refrigerating).
"but how do you boil and then refrigerate an entire pool?"
Setting: graphic animation — bright, even
A series of shots show a small, red excavator digging a large rectangular hole in a muddy, partially snow-covered backyard.
"So last year Thanksgiving, my brother and I came up with a plan, and then in the middle of winter, we started digging a hole in his backyard."
Setting: suburban backyard in winter — overcast winter day
Several clear plastic bins filled with different colored liquids (blue, green, red, yellow) are lined up on a countertop. They are labeled with painter's tape.
Setting: indoor workspace — indoor lighting
A shot of four clear plastic bins with different shades of orange and blue liquid. In front of them are measuring spoons and cups filled with white gelatin powder, showing different quantities.
"how much gelatin powder does it actually take to get to the ideal firmness"
Setting: kitchen/workshop — bright indoor light
Text: "1 Tablespoon", "2 Tablespoons", "1/3 Cup"
A hand tests the firmness of different colored Jell-O batches in clear plastic bins. One bin shows a person's bare feet stepping into green Jell-O, which breaks apart.
"how hot and then cold does the mixture actually need to get for the Jello chemical reaction to take place so it will actually get firm."
Setting: garage/workshop — indoor lighting
People (1):
• testing the Jell-O, not visible hair — not visible
A man attaches hoses to a line of six brightly colored 55-gallon drums (red, green, purple, light blue, dark blue, yellow) set up in a backyard.
"So we decided we could scale this up by using six 55 gallon drums with a custom propane burner underneath and a spigot we welded to the side, but more on that later."
Setting: suburban backyard — bright, sunny day
People (1):
• crouching and standing, wearing blue t-shirt and gray pants, not visible hair — focused on his task
Text: "55gal (208L)"
An animation of the Earth rotating, showing North America. A red 'X' appears over the state of Utah, indicating the location of the project.
"For that, we teamed up with Mother Nature and just picked the perfect location and time of year."
Setting: animated map — simulated sunlight on the globe
Text: "TDC"
A hand-drawn line graph on black paper shows nightly temperature fluctuations over months. A green overlay indicates the desired 'refrigerator' temperature range, while a purple overlay indicates the undesirable 'freezer' range.
"We needed refrigerator temperatures at night, but not freezer temperatures because that would freeze the Jello and our experiments showed that totally ruins it."
Setting: tabletop — direct, even lighting
Text: "Night temp (F)", "Jan Feb Mar Apr"
An animation of a calendar shows the months of the year. A small section of days in late April and early May are highlighted in green, representing the ideal time window.
"we knew we had about a three week sweet spot window towards the end of April to pull this off."
Setting: animated graphic — even lighting
Text: "JAN", "APR"
A clip from the animated TV show 'Phineas and Ferb' shows the characters and their friends happily playing in a purple Jell-O pool in their backyard.
"Our goal was to have a Jello pool party in his backyard that would make even Phineas and Ferb jealous."
Setting: Danville (Phineas and Ferb's town) — bright, animated daylight
A GoPro-style, wide-angle shot pans across the line of colorful barrels as water from hoses begins to fill them.
"So the plan was to start seven days before the party and fill the pool with an average of 10 barrels every day."
Setting: suburban backyard — bright afternoon sun
A man fills a large red barrel with water from a garden hose. Another man stands nearby. The scene is a time-lapse, showing them working around the barrels.
"first thing Saturday, a full week before the party, we got to work."
Setting: suburban backyard — bright, sunny day
People (1):
• standing and moving around, wearing t-shirt and shorts, not visible hair — in motion, focused
A man scoops white gelatin powder from a large paper bag and pours it into a steaming red barrel. Another hand adds red food coloring to the barrel.
"We didn't want to waste actual food. So this is just water and gelatin powder and food coloring, but there's no sugar."
Setting: suburban backyard — bright daylight
People (1):
• crouching and standing, wearing blue t-shirt and gray pants, short dark hair — partially visible
A montage shows the process continuing: stirring the red mixture with a wooden plank, propane burners firing under the barrels at dusk, and a valve on a hose being opened.
Setting: suburban backyard — transitioning from day to dusk
People (1):
• performing tasks, not visible hair — not visible
A clear hose filled with red liquid runs from the elevated barrels, across the green lawn, and into the empty, white-lined pool, beginning to fill it.
"We intentionally placed our barrels much higher than the pool. So when we were ready, we could use the potential energy to move the Jello from the barrels to the pool."
Setting: suburban backyard — bright sunny day
A time-lapse montage shows the entire week-long process. People work around the barrels, the sun sets and rises, and the pool level gradually rises with red Jell-O.
"We had to tackle about a thousand other issues that came up that I won't bore you with, but day by day and layer by layer, the pool began to fill up."
Setting: suburban backyard — cycles of day and night
People (1):
• moving quickly around the yard — blurry due to time-lapse
Two men carry a large, industrial swamp cooler on a wheeled cart across the lawn and position it at the edge of the Jell-O pool.
"my brother's neighbor Nick happened to have a spare swamp cooler in his shop. So we kept that running over the top of the pool pretty much the whole week."
Setting: suburban backyard — daylight
People (1):
• carrying a heavy object, wearing t-shirt and jeans, short hair — straining slightly
A simple 2D animation illustrates the concept of convection cooling. A cardboard swamp cooler blows blue 'cool air' arrows across the surface of a red 'hot Jell-O' rectangle, displacing a hazy red 'hot air' layer.
"This constantly replaces the boundary layer of air right at the surface with fresh, cold air that will suck out the heat more efficiently."
Setting: animated graphic — n/a
A time-lapse shot shows the backyard at dusk with dramatic, dark storm clouds gathering. The colorful barrels are still set up as people work on the final batch of Jell-O.
"And so, as we put in the final batch Friday night with ominous weather threatening to ruin the whole effort, at this point, we had done all we could."
Setting: suburban backyard — dusk, with dramatic sunset colors and dark clouds
People (1):
• moving quickly — blurry
A time-lapse shows the backyard at night. The Jell-O pool is covered with a white tarp and illuminated by work lights. People are gathered around a fire pit in the background.
"And so even if it didn't last long in the sun, I wanted to at least have the experience of seeing even a single belly flop on a smooth pool of actual Jello."
Setting: suburban backyard at night — light from the fire pit, work lights, and string lights
People (1):
• sitting around the fire — silhouetted
Two men pull a large white tarp off the pool, revealing the perfectly set, vibrant red Jell-O underneath on a bright, sunny day.
"And so we woke up Saturday morning with a forecast for a warm, sunny day and we pulled off the tarp to find a pool filled with actual freaking Jello."
Setting: suburban backyard — bright morning sun
People (1):
• walking backwards, pulling, wearing black t-shirt and rainbow swim trunks, short brown hair — focused
A hand presses down on the surface of the red Jell-O. The surface depresses like a firm gel and then slowly ripples as the hand is removed.
Setting: edge of the Jell-O pool — bright sunlight, causing reflections
People (1):
• testing firmness, not visible hair — not visible
Text: "youtube/markrober"
A young boy stands at the edge of the pool, arms outstretched like an airplane, preparing to jump. He then leans forward and belly-flops into the Jell-O in slow motion.
"And my brother asked if some of their friends' kids could have first dibs. And so with that, I'm happy to report this is what it looks like to belly flop in a pool of Jello."
Setting: suburban backyard — bright sunlight
People (1):
• diving forward, wearing dark t-shirt with graphic and red and black patterned shorts, short brown hair — concentrated
Text: "youtube/markrober"
A split screen shows a boy lying on his back in the Jell-O on the left, and on the right, another boy in a white shirt cautiously approaches the edge of the now-choppy Jell-O pool.
"Not yet."
Setting: suburban backyard — bright sunlight
People (2):
• lying on his back, wearing black t-shirt and black shorts, short brown hair — smiling
• crawling on the deck, wearing white long-sleeve shirt and patterned shorts, short brown hair — cautious
Text: "youtube/markrober", ""I'm OK""
A boy in a white long-sleeve shirt jumps into the Jell-O pool with a cannonball. Another boy does a belly-flop swim motion through the broken-up Jell-O.
Setting: suburban backyard — bright sunlight
People (1):
• jumping, swimming, wearing long-sleeve swim shirt or shirtless and swim trunks, short brown hair — laughing, excited
Text: "youtube/markrober"
The creator, now in the pool, emerges from under the red Jell-O, which has become more liquid and lumpy. He smiles and looks around.
"When I first got in myself, it was closer to the middle of the day. And one of the things we discovered was that direct sunlight over time had the effect of undoing some of the solidness of the lower layers."
Setting: suburban backyard — bright mid-day sun
People (1):
• surfacing from under the Jell-O, wearing black athletic shirt and not visible, wet, dark hair — smiling, covered in red Jell-O
Text: "youtube/markrober"
The creator is in the Jell-O pool, talking to the camera and describing the sensation. He wipes his face and gestures with his hands.
"When you go in, it just like fills your nose and like ears. It's a very surreal feeling of just being like, it's kind of hard to move,"
Setting: Jell-O pool — bright sunlight
People (1):
• treading in the Jell-O, wearing black athletic shirt, wet hair — expressive, talking, smiling
Text: "youtube/markrober"
The creator dunks his head under the Jell-O and comes back up holding a green and orange water blaster toy, smiling triumphantly.
"We have some pool toys uh hidden underneath. Got it."
Setting: Jell-O pool — bright sunlight
People (1):
• emerging from the Jell-O, wearing black athletic shirt, wet hair — grinning
The creator is sitting on the edge of the pool, holding a large, solid piece of Jell-O in his hands. He then takes a bite out of it.
"To keep it solid for even longer, if we were to do it again, we might put in a heat exchanger pipe system beneath the surface, sort of like how they freeze indoor ice skating rinks."
Setting: suburban backyard — bright sunlight
People (1):
• sitting on the pool deck, wearing black athletic shirt and rainbow swim trunks, wet hair — looking at the Jell-O, then biting it
Text: "youtube/markrober"
A slow-motion shot of a bowling ball being dropped into the Jell-O, creating a beautiful, crown-shaped splash.
"Now at this point you might be thinking, why would anyone spend the effort of six months of planning and then a solid week of backbreaking effort just to make a stupid pool of Jello?"
Setting: Jell-O pool — bright sunlight
Text: "youtube/markrober"
A clip from the TV show 'The Office'. Dwight Schrute holds up a framed photo of an Asian family, pointing to the man and identifying him as 'Jim' to the actual Asian man sitting at Jim's desk.
"This is Jim."
Setting: Dunder Mifflin office — fluorescent office lighting
People (2):
• standing over a desk, wearing dress shirt and suit jacket and trousers, brown, center-parted hair — serious, convinced
• sitting at desk, wearing light blue dress shirt and trousers, black hair — confused, deadpan
A wide aerial shot shows a large group of people, adults and kids, gathered in the backyard for a barbecue party around the Jell-O pool.
"Now that my curiosity was fully satiated and in my ongoing quest to be the favorite uncle, I told my nephews they could invite some of their friends over and my brother's family set up a neighborhood barbecue."
Setting: suburban backyard — bright afternoon sun
People (1):
• milling about, sitting, playing — not distinguishable
A man pours a bucket of lumpy red Jell-O onto a long black plastic sheet laid out on the grass, creating a slip 'n' slide that leads to the pool.
"the Jello was pretty broken down, but that didn't stop us from setting up a Jello pool slip and slide."
Setting: suburban backyard — bright sunlight
People (1):
• leaning over the slip 'n' slide, wearing black t-shirt and rainbow swim trunks, short brown hair — focused
Text: "youtube/markrober"
A young man gets a running start and slides headfirst down the Jell-O covered slip 'n' slide, launching into the pool with a big splash.
Setting: suburban backyard — bright sunlight
People (1):
• sliding on stomach, wearing shirtless and swim trunks, short hair — excited
Text: "youtube/markrober"
An aerial drone shot shows the full layout of the party, with the slip 'n' slide leading into the Jell-O pool, and people enjoying the festivities.
"And everybody starts to move."
Setting: suburban backyard — bright sunlight
People (1):
• playing, sitting, standing — not visible
Text: "youtube/markrober"
A montage of humorous fails on the slip 'n' slide. One boy tries to run on it and immediately falls. Another jumps feet-first into the pool instead of sliding.
"And I loved their sense of adventure, but it was a bit of an uncle fail moment because apparently none of them have ever used a slip and slide."
Setting: suburban backyard — bright sunlight
People (1):
• falling, jumping incorrectly, wearing shirtless and swim trunks, short hair — surprised, laughing
Text: "youtube/markrober"
The creator sits on the pool deck, wet and covered in Jell-O. He holds a small glass bowl of fresh, edible red Jell-O and a spoon, explaining the difference.
"We didn't actually put any sugar in here, so it's kind of disgusting. So we've got some real jello."
Setting: suburban backyard — late afternoon sun
People (1):
• sitting on the deck, wearing black athletic shirt and rainbow swim trunks, wet hair — smiling, talking
The creator and several teenagers are sitting on the edge of the pool, eating bowls of real Jell-O. In the background, a person in an inflatable T-Rex costume walks past the fence.
Setting: suburban backyard — bright sunlight
People (1):
• sitting on the pool deck, wearing shirtless or t-shirt and swim trunks, varied hair — eating, smiling