Sea Level Club
sex on the deck of a boat, presumably at "sea level"
Bored with the formal tour, my girlfriend and I went to the marine bathroom and joined the Sea Level Club.
At Sea Level Club
Similar to the mile high club in all ways except that this club is joined while on a cruise ship.
Wow the cruise was amazing; my girlfriend and I finally joined the at sea level club. This time we truly did move like the motion of the ocean!