Oh, the ball floats like a champ, even with a 200lb guy inside (technically, it's rated to 170lbers, and we tested it with those guys too). But its suction cup skin, which promises to form a number of tiny vacuums on the surface of the water to provide some level of traction, are completely ineffective.
The end result is more of a stationary hamster wheel than a go-anywhere invincible hamster ball.
However, it should be mentioned that the ball works incredibly well on land. And for the whole weekend we watched a group of giggling kiteboard instructors step inside before being rolled down ramps, stairs and small ledges.
So you can find $300 worth of fun in Hammacher Schlemmer's Six Foot Walk On Water Ball, but you'll encounter that fun on land, not water.
Note: You may recognize that guy in the video. Just maybe.
Shot by Joel Johnson, Edited by Don Nguyen