Shark Reef opens up the doors for something different to do. Located in Mandalay Bay, the aquarium is about a 40 min walk through and the ticket price includes: walking through the aquarium and a polar bear walk through.
There are definitely some interesting fish and sharks but don't expect the best aquarium you've ever seen. The tunnels with fish swimming remind me of an extremely small Atlantis. The polar bear walk through takes about 7 of the total min, including the several minute show (we almost missed it because it's located inside and they close the door during it).