The Aquatic Ape Theory was popularised by Elaine Morgan in the face of much antagonism from mainstream scientists. You can read more here. And see her talk at TED here. Essentially she argues that at some point in our evolution we adapted to being semi-aquatic; and describes several features common to humans, semi-aquatic mammals and aquatic mammals, but not primarily land based mammals.
The comments after the You Tube clip give you a real taste of the antagonism this hypothesis arouses!
And a more recent reference to the theory in The Guardian, 27 April 2013.
And in 2016, David Attenborough did a two part show on BBC R4 called The Waterside Ape. Aquatic Ape Theory as a label now being replaced with waterside ape. Some more on it here – http://www.riverapes.com
Meanwhile – however evolution ended up giving me the body I have, I shall enjoy immersing it in the brine and the chlorine.