Jupiter has no surface to set foot on, unless you count the hypothetical earth size rock inside all the gas. What would happen is that you would sink and get crushed long before you got to the rock.
Pedantry. (Well I suppose it's at least a valid point that without a solid surface there probably isn't anything for a human to want to bother visiting in the first place.)
This one presumably doesn't have a surface either, yet an earlier commenter spoke of surface gravity. Doesn't it surprise you in the slightest that two planets of the same size could have gravity that differs by such a wide margin?
