I heard that some people swam in Butcher's Knife recently... For a first-person account of the experience, you can watch this video:
http://www.youtube.com/watch?v=bPzqeX8J73cIt's big and long, helps to have a fast internet connection, but you may recognise a few faces in it... The video starts just below Pushbutton. A couple weeks later I would lose the camera in the eddy next to Garburator, after missing the little boof...
--C.