Atmospheric pressure is enough to crush a submarine or pop your ear drums. A diver can control his buoyancy through the amount of air he keeps in his lungs, regardless of which way his feet are pointed.
Fat, which has very little density, floats; iron, which has high density, sinks. However, iron ships can float and so can beach balls. Although, I've never seen a ship made out of beach balls, but I have seen iron ships.
Although, venus is smaller in size and mass to the earth, the atmospheric pressure is over 90 times that on the earth. So, a person would not merely be held to the planet's surface, they would become a permanent part of the planet's surface! Of course, the moon's atmosphere is so thin, they would float away, unless they had lead boots!