Stotan!

What in the heck is Stotan?!? That's the question  that has been haunting me as I started this new book by Chris Crutcher.  I know from prediction and literary clues that it is probably something to do with swimming and that it will be difficult for the characters to get through, but I don't know exactly what it is.  Guess I'll have to read a little more to discover this hidden secret!!