Float Tanks – or Isolation Tanks, as they were originally known – were invented in the 1950s by an American neurophysiologist Professor named Dr. John C. Lilly.  Dr. Lilly wanted to find out if the brain needed external stimuli to keep its conscious states going. One theory was the energy sources are biological and internal and do not depend on the outside environment.  Together with his associate, Dr. Jay Shirley, they worked on creating an environment where one was completely isolated from all external stimuli.  His first creation was a tank in which a person was suspended vertically, entirely underwater, head completely covered by an underwater breathing apparatus and mask. He continued experimenting and modifying the general design of the tank.   Lilly eventually found it more relaxing laying flat rather than suspended upright, if more salt was used for buoyancy. Other modifications were also made, such as water heaters with thermostats to keep the water at perfect temperature, air pumps to keep fresh air in the tank, and a water filter for the reuse of epsom salts. By the early 1970’s, Lilly had perfected the floatation tank in the way that is much used today.