The episode that will air next Wednesday, May 6th is called "Swimming in Syrup." I guess they got Cal Bear and Olympian Nathan Adrian to help out with the episode. Not much info available, but presumably they will test out how greatly increasing the viscosity of water affects swimming speed. I remember someone did a test like this a few years ago. If I recall correctly it was at the U of Minnesota. In that test they only made the water something like twice as thick and their results were that it did not affect swimming speed. Obviously there's more drag, but you also generate more propulsion because you have a thicker substance to apply force against.
edit: yeah, here's a story about the Minnesota experiment www.it.umn.edu/.../goingforthegoo.html
