Friend at high school in Australia had this in 1986. His dad brought it back from the US.

It was A4 or US letter size, softcover, full-colour picture book, all about a single fantasy dungeon complex.

There was a 3D double-page map at the start, and the rest of the book was full-colour illustrations from each room or region of the dungeon, often with an accompanying bunch of adventurers on a dungeon-crawl.

No text that I recall, aside from captions for pictures.

One picture was definitely a Gollum-style humanoid, called the Fisherman, or something similar. There was also a Lizard Man creature, and all the usual other fantasy-style dungeon monsters.

I thought it was simple called the Dungeon, but can't find anything to corroborate this. Don't know the artist's name either, and they did all the pictures.

Has been bugging me for years, so any help is gladly appreciated.