In the 1970s, Harry Palmer floated continously in an isolation tank for 8 weeks. He developed a perfect awareness in the tank. After that, he drained the tank and never bothered with floating again. He went on to create the nationally recognized and quite potent Avatar spiritual system based on his floatation experiences. He wrote about his experiences in a highly entertaining fashion. You can get his book in PDF form for free or grab it from Amazon. Or heck, you can download it from this site too.