Dolphinarium

Dolphinarium was a fictional swimming pool seen in The Beano.

The Beano Summer Special 1981's front and back cover featured various characters at Dolphinarium. Dennis the Menace and a black dog were seen above the pool. (TV: The Rings of Akhaten)

Information from invalid sources
Another source agreed with the depiction of Dolphinarium in the issue. (NOTVALID: The Universe is Calling)