Guests are given color-coded tickets which tell you which submarine you are to go on. The passenger transfer operation is very efficient. Guests from the previous tour disembark each submarine and the new passengers then proceed to board the submarine.
My ticket was for the 48-passenger submarine, so I had to wait until the boarding was completed for the Atlantis XIV. The Discovery them made the quick trip over to the smaller submarine which had just surfaced. My Atlantis submarine adventure was about to begin.
I was the first one to board the submarine. I climbed down the 7-step ladder and was fortunate to be directed to a seat right down by the submarine's captain and co-pilot/narrator. The seating is a bit tight, but each passenger gets a view port. Headsets are provided for those requiring narration in another language. Our co-pilot was doing an English narration, so I didn't need a headset. My fellow Japanese guests did. I presume that the live narration on the Atlantis XIV was in Japanese since all of the guests on that submarine appeared to be Japanese visitors.