Is water less dense than the human body?

The average human body has a density of 1.010 kg/litre

The density of pure water is exactly 1 kg/litre

The density of sea water is 1.025 kg/litre

So the average human is denser than fresh water but less dense than seawater.

There are significant differences in density between people, women tend to be less dense than men, muscular people tend to be more dense, fat people tend to be less dense. We can also reduce our density by breathing in deeply.

Incidentally dead bodies tend to float after a few days due to the build up of decomposition gases within the body reducing its density.

Sources

Density of human body - http://en.wikipedia.org/wiki/Orders_of_magnitude_(density)

Density of sea water - http://en.wikipedia.org/wiki/Sea_water