The tank was invented by John Lily, pioneering neuronaut. They are wonderful for thought and introspection. The problem with the bathroom version is the exquisite temperature control (93F , skin temperature) needed to keep the illusion of no skin boundary. Moist warm air is needed to keep a sensation of cooling from evaporation. Also, depending on your dwelling structure, with your ears in the salt water, you can detect any small floor vibrations, foot teps, trucks rumbling in the distance. All the se small sensations provide areminder of the body, and break the spell...When near perfect conditions are attained, the sensation is limitless and transhuman ! -Jay