I remember there being a dungeon for D&D 5e, possibly as part of an AL adventure (I don't remember it being in a full published adventure like Out of the Abyss, etc), but if it was AL, I don't remember which season (probably one of the earlier ones, though), or exactly how long ago it was. Me thinking it might have been AL might be a red herring.
It was a small dungeon, I feel like it only had 8 rooms or so, arranged in a spiral shape, and near the centre of the dungeon, I want to say area 7 but that might be wrong, there was a little alcove-like room with a shrine to Dagon there, and possibly a dead/undead creature or two in there. After this room, there was then the centre of the spiral, which contained the "boss fight" (I can't remember what this boss fight was either).
I can't remember what Tier this was for, but it was probably Tier 1, or Tier 2 at most; I don't think it was higher level content.
That's all I remember, although comment-questions may prompt me to remember a little more...