What is the approximate depth of the water in this unusual-looking exhibit? Also, how many aquariums did you visit while in Japan? Did you pick up lots of maps?
The water is around 2-3 metres deep, with underwater viewing all around the tank.
I visited 6 Japanese aquariums and I think I've got you at least one edition of the map from each of them. I'll be in touch via PM once I've got a few more ready to ship to you.
@snowleopard I couldn't give you an exact depth but the water is deeper than this photo makes it appear. Definitely the most spacious of any penguin exhibit I've seen in Japan, but I'm personally not a fan of the dim lighting.