I believe Hampstead station is the deepest insofar as it is furthest down from the surface, but which tube station is furthest below sea level?
It is indeed a long way down inside the station, but Bank etc are on a small rise well above river level - on the surface it's a notable pull up from the river bank.DLR platforms at Bank maybe? I know its not a tube line but its part of the Bank Monument complex, and located under the Northern & Central platforms.
My reading suggests Waterloo Jubilee at 74m (ie 26m down) is lowest?