Once, just once I went into the Diving Bell. We were promised a look at a giant octopus down, down in the water. This would be in the mid '40s. The water was about as murky as a algae filled swimming looks now. The "octopus" was probably rubber, very still and barely visible through the murk. I don't think any marine life would have survived in that water.
But hey! What about the Goofy Village. Optical and physical illusion type place, where down seemed to be up, water apparently ran uphill, and your senses were completely thrown off.