The concept
When I was a kid I remember holding a bucket over my head and walking into a lake. As the rim of the bucked reached the water the noise and chaos of the beach dissolved away and I was suddenly in a beautiful tranquil world lit with soft shimmering light. The sweet smell of the water and the sound of my own breath filled the air. There’s something simply magical about it.
For me this experience was the catalyst to an idea that took another 15 years to become realized. As I got older the magic of that bucket never left my memory. One summer when I was about 13 I remember spending lots of time under a capsized canoe, wishing I could make a room underwater. I began daydreaming of a way to make an underwater room a reality. My initial (unrealistic) concept was to take a large plastic water storage tank and cut the bottom off. Then, using a complicated system of chain hoists, I-beams, cables, and ratchets the plan would be to submerge it like an upside down cup into a body of water. I thought it would be awesome to bolt benches around the inside so you could actually get completely out of the water – under water.
Of course there are many reasons this was relatively unrealistic:
- I’m poor and couldn’t afford a tank like that ($1,000+)
- A 2,000 gallon tank would have more than 16,000 pounds of lift (anchoring would be an issue)
- I would need a crane to get one into a lake
- I don’t own a lake
- I was only 13
So the idea of an underwater room sort of just simmered in the far back of my mind for years. Then one morning in 2006 I got an excited call from my little brother Jordan, he was explaining to me how he was taking a shower and had this idea of building a room underwater!
Jordan’s idea involved using thin plastic sheeting and submerging it like a parachute while trapping a large bubble of air. I frantically shared my idea of an underwater room and all the problems I thought it had. We knew my idea was not realistic but we also figured that simply attaching plastic sheeting to a rock would probably not be strong enough. We concluded that we could increase the strength of the bubble by wrapping it in a net to help distribute the force.
The prototype
We quickly tracked down some nylon construction netting with 3″ square holes and some “clear” 6 mil plastic sheeting and we headed to the lake. We brought scuba equipment, some climbing webbing, and my dad to help out. We scouted a spot to anchor it on a giant granite boulder about 20 feet deep and attached our net. We put the plastic under the netting and began to release a bubble of air from a scuba tank. By the time the bubble was roughly the size of an ice chest everything had stretched 10-15 feet up to the surface of the lake.
We had a feeble “proof of concept” but we knew we would need to make something stronger, bigger, better, and easier.
Nerdy side note: the buoyant lift of a bubble is equal to the weight of the water that the bubble displaces. Water weighs 8.34 pounds per gallon. Submerging an upside down 5-gallon bucket would take 41.7 pounds of downward force.
At this point we decided to shorten our tethers and try to stress the system to its failing point. We wanted to see where the weakest point was so we could improve the design. As the bubble grew quite large we were carefully watching and listening to all of the parts. Eventually, in a surprisingly quick snap, all of the strands of the netting at one of the four corners broke where they were tied together and the giant bubble went rushing to the surface.
It’s worth noting that I think it’s highly unlikely that all the strands broke “at once”; our theory is that all strands were stressed and that one strand broke, which very quickly dumped all the force it was carrying onto all of it’s neighbors. This set off an incredibly fast chain of events that seemed like a unified “snap”.
Solve the problems, improve the design
It was obvious that the concentrated forces on the corners of the net was our weakest point. I suggested that we make a strong structural ring to attach the net to. This would help distribute the forces on the net and it would give us something solid to anchor to the ground. We made the octagonal ring out of 4-inch steel well riser pipe with 1/4″ wall thickness (free scrap find). The ring is about 7 feet in diameter. All around the perimeter of the ring we welded 48 1″ long steel posts. Each post is an attachment point for the net.
To set up the net we draped it over a dome tent to get a hemisphere shape and threaded a piece of climbing webbing around the perimeter. We evenly spaced 48 loops of 7-strand para-cord around the webbing. Each para-cord loop connects to one steel post. Since the “ring” is actually an octagon the distance from the posts to the center of the ring (the radius) varies from post to post; this means the loops are different lengths. In order to keep things organized we used blue para-cord for the corner loops and white for the rest.
We also found that the “clear” visqueen is far from clear, it’s closer to non-fat milk at best. So we got some crystal clear vinyl from our local fabric store.
Time to head to the lake! After a little scouting with scuba gear we found three extremely large rocks that were spaced about right and an easy swim from a secluded shore. We wrapped large stainless steel cable (free scrap find!) around the rocks and attached everything with cable clamps. Getting the ring height correct was tricky but after quite a bit of underwater work we were happy with it.
We hooked the net to the ring and passed the vinyl under it. Using the purge button on our spare regulators we put a large bubble under the vinyl. Soon the metal ring began to lift off the sandy lake bed. At this point we adjusted the vinyl a bit then filled it up the rest of the way. It all worked exactly as planned!
The result is an incredible, magical, and strange room 15 feet below the surface of the lake. When in the room you are standing on the lake bed, your toes are about 20 feet below the surface with your shoulders out of the water. It’s bright, loud, and totally awesome!
The room has some very interesting attributes:
- The net produces an interesting “bug eye” effect that effectively creates a grid of lenses that multiply your view of the outside world.
- Because the water is so cold any humidity in the air very quickly condenses on the inside surface of the vinyl.
- When the lake is exceptionally stormy the room is quite calm however as large swells build over the room the pressure temporarily increases, then as the swells pass (and the “valley” of the wave goes over the room) the quick reduction in pressure produces a cloud inside the room! The cloud appears and disappears in rhythm with the waves on the surface.
The Bubble Room all over the internet
- Our original video that went viral can be found here: The Original Underwater Bubble Room
- If you’re interested in some of the math and physics I wrote an article about the forces on the cables here
- We were featured in the National Geographic series called Mad Scientists (for a different invention), at the beginning of our episode we take the host on a quick trip to the Bubble Room. You can watch the show preview here: Mad Scientists: Biggest Teeter-Totter Ever
- In the Discovery Channel show You Have Been Warned (Outrageous Acts of Science in the US) the Bubble Room was featured at number 3 in their top 20 countdown. (Season 2, Episode 12 “Hackaverse”)
- The Bubble Room was featured in the boingboing article Inside a Nevada family’s underwater fort
- Make Magazine also did an Underwater Bubble Room article
- in 2010 Jordan and I did an interview on NPR about the Bubble Room. Listen here
- If you really want to see a LOT of footage of the Bubble Room here’s a much longer video that shows everything you could want
