Wild Amazonia - Amazon Flooded Forest

A short underwater tunnel through the Giant River Otter exhibit, that houses a breeding pair. There is another full-height underwater viewing window as well as an expansive view of the land area above.

With this new addition (underwater tunnels) to many zoological parks, i wonder what are the least common/weirder?
Aquarium tanks, Polar Bears, Sea Lions, Seals, Penguins, Otters, Manatees, Dugongs... is there any other speices with this feature in their exhibits?

While not underwater, the "tunnel" in the Bronx Congo gorilla exhibit is pretty unique and effective.

An underwater tunnel for giant otter viewing? Outstanding!