> There's something I don't understand in this statement and in GP's story: when you stay static in the water, provided you don't carry extra weight, you just naturally go up and float to the surface. If you want to stay down, you have to actively move in order to counter Archimedes' force.
If you've got a lungful of air. Exhale first, and most people will sink like a stone.
My Dad had a trick, which I've done a few times myself as an adult, where he'd hyperventilate for a bit to get his blood heavily oxygenated, then exhale fully and just lie quietly on the bottom of the pool for a minute or so. (In the shallow end, so he only needed to stand up to breathe.) It's surprisingly soothing; after reading this thread, though, I'm not sure I'd do it at a public pool to avoid freaking out the lifeguard, and I certainly wouldn't teach any kids to do it.
(Floatation also depends a lot on your body fat percentage. Babies are very chubby, so they float, but I can imagine that a real lean kid in the middle of a growth spurt wouldn't be so buoyant.)
If you've got a lungful of air. Exhale first, and most people will sink like a stone.
My Dad had a trick, which I've done a few times myself as an adult, where he'd hyperventilate for a bit to get his blood heavily oxygenated, then exhale fully and just lie quietly on the bottom of the pool for a minute or so. (In the shallow end, so he only needed to stand up to breathe.) It's surprisingly soothing; after reading this thread, though, I'm not sure I'd do it at a public pool to avoid freaking out the lifeguard, and I certainly wouldn't teach any kids to do it.
(Floatation also depends a lot on your body fat percentage. Babies are very chubby, so they float, but I can imagine that a real lean kid in the middle of a growth spurt wouldn't be so buoyant.)