the semi sub is decent - not sure if it was worth the money $30 or something. you're essentially in the hull of a mid-sized boat looking out of small windows. you do get to see a good variety of fishes in the corals and such. the ride is smooth. it's definitely not the most exciting thing.

depalm island has a very shallow coral viewing area with their marquee parrot fish or something (huge blue fish). the serve buffet comprised mostly of finger foods - hot dogs, etc...the waterpark wasn't opened when i went.