Violently gushing lava bubbles, that's what. Word around the internet is that unless you're sporting a hyperalloy endoskeleton, chances are you're not dense enough to actually sink into a pool of roiling magma.
This has to do with the fact that lava is more than three times as dense as water, and well over 100,000 times as viscous. Wired's Eric Klemetti compares a human trying to dunk him- or herself in lava to a piece of styrofoam floating on a pool of motor oil. Sinking obviously becomes even less feasible, when the lava begins to cool and forms a crust. Submersion just isn't going to happen.
But just for fun, let's take a look at what would happen if you decided to commit lava-cide by doing something outrageous — like, oh, I don't know, doing a cannonball from a height of 80 meters. That's how high the people in the video up top were when they lobbed a 30kg bag of organic waste into the lava lake at Ethiopia's Erta Ale volcano, and it looks like it managed to penetrate the lava's crust just fine, thank you very much.
Still, one can't help wonder if this bag managed to penetrate the lava precisely because there was a thin crust over the lava's surface. How might this scenario have played out had that bag landed in a pit of hot, fresh lava? After all, coming into contact with water is said to be comparable to landing on concrete at high enough speeds. Given that that bag was dropped from a height of 80 meters, it was traveling close to 90 miles per hour by the time it reached the lava. Hitting water at 90 miles per hour is a frightening enough thought as it is. Hitting something three times as dense, and up to a million times as viscous as water at 90 miles per hour? It makes me a little sick just thinking about it. [Photovolcanica]