I entered the isolation tank once under the influence of 600 mg of mescaline.
I will say that it is the deepest I have ever gone. There was no time, no location, no me; there was only my awareness existing within the tank. There are few other feelings like being totally stripped from the sensory world. Extreme meditation.
I now dream of opening an isolation tank center later in life so others can have this experience. I would go more now but it is very costly in my area. Once I am able to purchase my own I will definitely do so.
"Think for yourself and question authority." - Leary
"To step out of ideology - it hurts. It's a painful experience. You must force yourself to do it." - Žižek