As have been said it is a classical plot and probably one that the elder GMs here have tried variants of. Jules Verne and his Captain Nemo as well as the recent Pirates of the Caribbean films do come to mind.
As for the dungeon itself: It is obvious that you put much labour into this. It is well written and very interesting at times. However I cannot escape that feeling of deja-vu. It all feels so predictable... A series of fights so the party can get treasure. A big nasty Pirate Captain and his pet Crocodiles.
Regardless: You have done well and the Citadellians obviously cherish your work. Congratulations! Go to Comment
Deja-vu can't be helped. It's an olde skool plot that kinda follows a predictable formula. I tried to punch it up with the mad prisoners and Threll the thief, but it's mainly meant to be a well-done classic dungeon. Go to Comment