The water inlet is at the surface behind the right hand wall. The glass box is a viewing area, but I think it was closed as a Covid precaution, as is the warning sign. The green area of the pool is the deep part, the area near the windows is shallow.
The window on the right allows visitors to see the otters swimming at the surface when they are at the top section of the ramp. There is a larger window on the floor below so visitors can see the otters when they dive.