Love the theme, love the map (especially how it changes from tan to blue as you go underwater) and even though I personally don't like the cover art at all, it really does look like some blueprint of a lost contraption that Daedalus was cooking up, so it really helps set the vibe!
This is a straight forward adventure with some nice treasure, interesting magic items, and very dangerous foes. This location is FOR SURE getting dropped into my current BECMI game!
Only thing this is missing is scale on the rooms/maps. Oh, and it would be nice to see some more interactivity and larger scale with the submerged Labyrinth (maybe some sauhagin gladiators or some other cool stuff) if you plan on doing a redux.
All and all, great job!