Here is a link showing these snails in their natural environment, scroll down several photos and you will see them (in deep water)
http://www.planetinverts.com/sulawes...er_photos.html
I agree with Andrew that these snails live in very deep water as well as shallow areas and have a gill. They will not drown without surface access.... Burrowing would be no more problem for them than it is for a MTS.
Cheers, Bill