I'm pretty sure it was ice, and he was inside it, but whether he did do it on will power and with no help at all is anyone's guess. They made a hollow in the centre of the ice to be wide enough for him to stand in it, as if he touched the ice with his skin for any long period of time, he would have stuck to it and most likely had lots more complications. He had a tube to pee into and took laxatives 2 days before to flush out his system. He took a jumper in with him and had a hat and thats about it. I watched a programme where he explained what he went through and at one point he was hallucinating and when he came out his ankles were about 3 times there normal size. Would recommend his autobiography for all details on his stunts (also chance to win $100,000 if you work out underlying clues and go to America to look for it) - its actually a really interesting book.