A Comprehensive Guide to the History of Floating
                     A Comprehensive Guide to 
the History of Floating
History
John C. Lilly, a medical practitioner and neuro-psychiatrist, 
developed the flotation tank in 1954. During his training in 
psychoanalysis at the US National Institute of Mental Health 
(NIMH), Lilly commenced experiments with sensory deprivation. In 
neurophysiology, there had been an open question as to what keeps 
the brain going and the origin of its energy sources. One hypothesis 
was that the energy sources are biological and internal and do not 
depend upon the outside environment. It was argued that if all 
stimuli are cut off to the brain then the brain would go to sleep. Lilly 
decided to test this hypothesis and, with this in mind, created an 
environment which totally isolated an individual from external 
stimulation. From here, he studied the origin of consciousness and 
its relation to the brain.
Tank Design & Usage
In the original tanks, people were required to wear complicated 
head-masks to breathe underwater and uncomfortable tight clothing 
that constricted the blood flow in certain areas, but the mask and 
clothing detracted from the isolation experience. The tight fit of the 
mask seal around the face and the retention strips wrapping around 
the back of the head were uncomfortable in long sessions. The 
constant hissing of the air valves and bubbling of exhaust air out of 
the mask prevented the possibility of silence. The faceplate of the 
mask was typically solid black for visual isolation, but then the tank 
user needed help entering and leaving the isolation tank since the 
mask blinded them. The tight neoprene clothing was extremely 
uncomfortable in sensitive areas such as the genitalia, and 
constricted blood flow and mobility in other areas.
In newer tanks, epsom salt is added to the water in the 
tank to increase the density of the water so that the 
subject floats with the face above the water. However, 
since the ears are submerged when the subject is in a 
relaxed position, hearing is greatly reduced, particularly 
when ear-plugs are also used. When the arms float to the 
side, skin sensation is greatly reduced because the air and 
water are the same temperature as the skin, and the 
feeling of a body boundary fades. The sense of smell is 
also greatly reduced, especially if the water has not been 
treated with chlorine.