After the excitement of cat toast yesterday, I have two videos for you today.  Have you ever wondered what happens when you put liquid nitrogen into a swimming pool?  Me neither, but turns out it is rather dramatic….

And here is a little thing that a created on holiday….

Hope that you enjoyed them!  Does anyone know whether it was dangerous to swim in the pool after the liquid nitrogen was thrown in?


  1. Looks like it was outdoors … but swimmer might have passed out from asphyxia in the ‘cloud’? There have been fatal accidents with liquid N2 asphtxia in confined spaces / basements in the UK.

  2. My terrible knowledge of science made me wonder if after she jumped in, if she’s bob back up to the surface as a frozen block like the T1000 in Terminator 2.

    I get all my scientific knowledge from action films.

  3. I don’t believe there would be any danger with that amount of water and LN2. The cloud you see isn’t nitrogen (it’s water vapor), and the nitrogen gas would disperse rapidly in any well ventilated area (and it’s worth remembering that nitrogen composes 80% of our atmosphere to begin with). Since LN2 is less dense than water, it would remain on the surface of the pool and boil within seconds. For that reason, I doubt the LN2 would have had any measurable effect on the temperature of the pool’s water.

    By far the most dangerous feat accomplished in this video is carrying that amount of LN2 without protection and container.

    1. Totally agree. Not much of the nitrogen even entered the water. Bet the air above the pool was cold though.

  4. When I did my PhD I had to use liquid nitrogen, and I used to love playing with it. I did throw it in a waterbath once or twice and all it did was great theatrical effect of “white smoke” and freeze a thin layer of water, which I used to pick up. Water wasnt particularly cold after the liquid nitrogen either,

  5. A little to add – N2 is lighter than air, so a mass of gaseous N2 would rise somewhat in air, unlike gaseous CO2 which is heavier than air and would stay on the surface of the water (absent strong breezes).
    So there would be little danger of anoxia swimming in the pool – there’d still be some O2 to breathe.

    As already pointed out N2 is most of the air we breathe (78%, gang, not 80%); and I agree the most dangerous part of that stunt was carrying liquid N2 in an open container without protective gear.

    We all know that the body does not sense lack of O2 when breathing, right? All we sense is too much CO2. So IF the nitrogen stayed on the surface, the swimmer could breathe pure N2 without discomfort, and pass out. But N2 doesn’t stay on the surface, so all is safe.

  6. That liquid nitrogen video is absolutely ancient. I believe it was one of the first videos I ever watched on YouTube!

  7. I’ve handled LN2 for years and the dangers are VERY over rated.
    I’ve seen someone drink it and I’ve spilled it on my hands and arms to no ill effects. The reason the man carrying it was ‘in danger’ is because of his clothes which can trap an amount and hold it against his skin which will then freeze.

  8. That was at Penguicon in 2006, and was the first time we got LN2 to play with and make ice cream. Now the nitrogen in the pool is a tradition for closing the con. Check out the video from 2010, where we had a bigger pool and a LOT more nitrogen:

    It’s even hosted by Howard Taylor (who was the man behind the camera in the video above)!

  9. Speaking as a chemical engineer, nitrogen may be lighter than air, but only by 3% or so, meaning it doesn’t rise fast. The cloud over the water is undispersed nitrogen vapour; very similar to the carbon dioxide cloud you exhale in cold moist air. You can breathe it without harm, but it would be like taking a lungful of helium — interesting but not effective at keeping you alive. Yes, nitrogen makes up 78% of air, but it’s inert. It’s the 20% of the air that’s oxygen you need. Breathing a nitrogen cloud would feel like breathing, but it would be the equivalent of getting no breath at all from an oxygen perspective. In fact, the cloud isn’t even 100% nitrogen; it’s probably about 80% nitrogen and 20% air, so it would be like breathing half way up Everest or in La Paz, Bolivia; laboured but somewhat effective.

    Note that when the person gets in the pool, the cloud moves away. That’s because there’s not much air circulation in a hotel’s pool area. The act of jumping in moves the air around, and pushes the cloud away.

    Is it safe? Sure, so long as you don’t stay breathing nothing but the cloud, and you exert yourself. The nitrogen stops being being liquid at -196° C or -321° F; throwing it in the pool means it goes to a gas virtually instantaneously as it rapidly warms up. It needs a fair mass and no surface area to stay in a liquid state (throwing it disperses the mass and radically increases the surface area, causing it to rapidly boil). So it’s not cold from basically the moment he throws it. He could throw it on a parking lot and achieve the same effect.

  10. Good new: nitrogen (even liquid) is not dangerous! About 78% of atmosphere is nitrogen. And do you know we use nitrogen to keep the wine good? So it’s absolutely not dangerous.

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