Unfortunately, sometime in the mid '90s, waterbeds started to go out of style. Some argue that they don't provide enough back support, but they are so much fun to play on.
If you've never had the pleasure of playing on a waterbed, a 140-pound blue great dane named Nessie can prove just how awesome it is to frolic on a gigantic waterbed. Although, her waterbed is actually a pool cover, but pretty much the same thing.
In the YouTube description, Nessie's owner clarifies that her dog has been playing on the cover since she was a pup, and that her dog's wellness is her priority. But still, don't try this on your own pool cover.