Mile deep club

The hardest of all the "mile clubs" to get into, to get in, you have to have sex in a submarine, a submersible, or a bathysphere.

Richard: FUCK YEA!
Mike: what?
Richard: I'm now a member of the mile deep club!
Mike: what the hell is that?
Richard: Its like the mile high club, except you have to have sex in a submarine.