I'll toy with it for a couple of days and nights and see what happens, Shantak.

With the passing through solid objects thing, could you not just pass a hand into the ground and continue to pass more and more of your body into the ground until you are completely underground and then continue to descend? (Flying is more my thing, don't know if that would work for me). I suppose you could continue to descend until you reach magma. Like with flying up, you should've been dead within seconds of passing into the earth by suffocation and would definitely be dead by the time you reach magma!