The spotted seal phoca largha exhibit at the Shinagawa aquarium in Tokyo, Japan, offers great visitor views thanks to two 360-degree glass tunnels, and a large step-in all glass cylinder. There is also a flat acrylic glass panel of about 4 meter length and 2.20 meter height, and two hemisphere-shaped viewing windows. All transparent elements are made of acrylic except for the tunnel floor, which is made of glass.
For the seals I would have liked to see more water surface area, possibly with some water movement (wave machine or jets), and a larger beach area, but otherwise this exhibit had a lot going for the animals: exposure to the outdoors, and it is probably the deepest seal exhibit that I have seen in my life.
Here is a link to a video that gives a quick overview of the lower part of the exhibit.
And another one:
Here I am standing in front of the flat panel looking into the exhibit. There is a 360 degree viewing tunnel to either side, and two hemisphere windows straight ahead in the rockwork.
I'm following a seal around.
Stroller in the tunnel - above
The tunnel is not round but elliptic, which I think led to less distortion if looked straight at it. It also was good because there was no risk of hitting your head against the glass, or having to make it unnecessarily large because of the head height. Click on photo to enlarge.
Step-in cylinder - above
Here I am standing in the center of the exhibit in a room with glass all round and above except where the two 360 degree viewing tunnel connect. You can see the concrete support structure for the tunnel on the right (black). The ceiling is slightly tilted - you can't see it well in the photo, or even notice it while visiting, but when I reached up I could tell that the ceiling was from about 2 meters to 2.2 meters on the high end near where the two 360 viewing tunnel connect.
Kid on glass floor - above
A kid is standing on glass. The surface has some anti-slip feature. I'll post detail photos soon.
The layout and the viewing would make this a great penguin exhibit. The only problem is the height difference between above and below water viewing. At the Shinagawa Aquarium they solved this with a staircase for the main visitor flow and an elevator for wheelchairs and strollers. The day I was visiting, on a Sunday afternoon in April, it worked quite well but neither solution is ideal for large crowds.
A bubble machine doesn't sound very exciting and yet I thought here at the Shinagawa seal tank it was effective, inciting and mesmerizing. Adding a nice touch to the tank. The machine throws out bubbles that if the water is calm turn into beautiful circles on their way up. And every other minutes it erupts with a bubble curtain. Best of all: I can't imagine this being expensive or high maintenance.
When I was there the seals where so active that most bubble circles broke up pretty fast - but who cares if you get to see beautiful seals zooming by. But when there was a moment of calm it gave you something else to look at until the next animal came racing around.
I found a video below, done by slaiyee that gives you a good impression of the bubble machine.
There are lot more details and other features to this exhibit. I will post them within the next couple days.