We did the Atlantis sub thing last year in Hawaii and it was great fun. My wife was scared stiff...She thought it was one of those glass boats. In any case, when she saw some kids boarding she changed her mind. She enjoyed herself. By the way, it seems that sailors like to take a tour, because, unlike their subs, they can actually see something.
Their fleet of subs is larger than most countries sub fleets! Go and enjoy!