watever u do, KEEP HIM OUT OF THE WATER!!! i had one do this and it drowned because of the weight
u need to cover land area gravel with substrate
is he sitting with his arms under his chin and hunched over? if so it's not good! if he's laying straight pressed against the soil with elbows bent and to his side he should be ok, that's what mine look like when hibernating
wat is the daylight photoperiod and temperature like?