The aquatic ape theory claims that many of our features can ONLY be explained in the light of an aquatic, or more likely semi- aquatic stage that our anscestors underwent in the past, after we had split from the apes, during the period known as the fossil gap.
It is an alternative to the currently accepted 'savannah' or 'mosaic' theories about human evolution.
Since this page is under construction, you may wish to read the leaflet that was given out at Elaine's recent(ish) talk in America. It gives considerably more evidence. Turn autoloading images off before entering it if you have a slow link.