It all started . .
In 1954, John C. Lilly, M.D., invented the first isolation tank, which was simply an 8 foot cube filled with ocean water. Completely submerged, wearing a mask with oxygen, he used this prototypical tank to further his exploration of the limits of human consciousness.
By the late 1960's, Dr. Lilly had the idea of floating in a supersaturated solution of epsom salts. This solution was found to be non irritating to the skin, while at the same time buoyant enough to keep the body naturally at the surface of the water, eliminating the need to wear an oxygen mask. By completely enclosing the water, maintained at skin temperature, Dr. Lilly was able to create a unique environment for meditation and scientific research..
"By attenuating vision, hearing and the proprioceptive sense, and floating at the surface so that the gravitational field is reduced to the minimum, you can relax every single muscle. Even your ear muscles, your neck muscles, your hands, your arms, your back, and so on. You can find the ares where you are holding needlessly, and you can let go. Once you do this, and go through all this, and get the inputs to the brain down to the minimum possible, you suddenly realize that that is what has tied you to consensus reality, and now your free to go."
"The first thing you get is physiological rest. You're free of gravity; you don't have any more of those gravity computations that you do all day long. Finding where gravity is, and in what direction, and computing how you can move and not fall takes up about 90% of your neural activity. As soon as you start floating you're freed of all the gravity computations you've been doing all the time, so you find you have a vast piece of machinery that was being used for something else and you can now use it for your own purposes. For example, you can instantly feel that you are in a gravity-free field. It's as if you are somewhere between the moon and the earth, floating, and there's no pull on you. As soon as you move, of course, you know where you are, but if you don't move, your environment disappears and, in fact, your body can disappear." (John Lilly, from Tanks for the Memories; Floatation Tank
Talks, by Dr. John C. Lilly & E.J. Gold.)