National Aquarium: Black-tip Reef

 The last time I visited, the mainstay of the Aquarium was the large Sting Ray and Shark Pool.  Since then they've redesigned it and repurposed it into a combination sandbar and coral reef with a school of Black-tip Sharks anchoring hundreds of other fish included two large rays and a Green Sea Turtle with one flipper amputated.

You can see it from multiple angles and vantage points from above and there are also below surface viewing windows.

 Against one side you can see into the adjacent Shark Alley exhibit.

 Overhead there is a skeleton of a Right Whale.