What a bunch of lemmings. Considering the authorities dug ditches specifically to keep people away tells me this is just Darwinism doing it's work. Looking at the survivors, I doubt they'd have contributed to society anytime in the near future.
Funny story: when I was 7, the neighbor kids had their cousin over - first black kid I ever met. We went swimming and I didn't believe it when everyone said he couldn't swim...so I pushed him in. He was 4ft tall and "sank" to the bottom, which was 5ft down. First time I ever thought to myself, "WTF?".
How much air do you put in your legs when you inhale? I don't fucking float. I've taken water survival courses.
No human will float like a chunk of foam, nor will any sink like a rock, although some appear that DENSE... Suck in & hold a full breath and you've just decreased density at your CORE from the air cavity you created with your lungs. I know when I inhale, my arms & legs are a little more boyant, probably due to more blood, which is less dense than your limbs. I have to exhale to actually sink. I know this because I was just swimming in the lake.
Even if the best you can do is keep your scalp at the surface, it takes a few flicks of the wrist to stay above. It's a simple "british wave" towards your feet - you're pushing water downward to create upwards lift. It's simple as fuck. If you're out of shape, chances are you'll need less effort to float - fat people float better. The link below (page 4) shows that animals get damned near the same density of water when they hit 25% body fat. Well over HALF the US population is at that point, or higher.
http://jn.nutrition.org/cgi/reprint/112/2/398.pdf