Question

What will happen when you jump into a volcano? Would you sink or what?

Answer 1

I think you might sink slowly, but you'll also burn. 

Answer 2

You wouldn't sink. Your lungs would either:
A.) Disintegrate
B.) fill with smoke
or C.) they would Char.
All of these would result in death. So basically, jumping into a volcano will destroy your lungs before anything else