If you look at the left side of the picture, you can see the late Ross Pavlac's right foot extending dangerously close to the edge, and in the original photo you can see that he is up on the toes of his left foot. Ross fell into the pool, then got out and pushed Denny Lien (wearing a cloth cap, just to Ross's left) into the pool, claiming that Denny had pushed him.

Note that Keller wasn't wearing shoes. He had also put aside his wallet, and was in general much better prepared for a swim than Ross and Denny were.

Update by Denny Lien: I did in fact push Ross in, but it was sheer clumsiness on my part and was not deliberate. To make amends, I then volunteered to allow myself to be thrown in as well, and this happened -- I no longer recall if Ross did the honors on me himself or not, though.

Photo by Bob Webber
Information updated by Denny Lien