An Archipelago as a Dungeon
RPG dungeons often presume a lot of separation between rooms. Anyone starting a fight in this dungeon would immediately tip off all creatures. We can excuse our way around it with oozes, deaf goblins, et c., but it's a heavy restriction that seems to receive less attention than it should.
It also seems odd to find enemies separated. Why does Keraptis, in White Plume Mountain, have all of his minions waiting in different rooms with one magical item each? Why not have them together?
Why don't more dungeons have foes who run back, get the rest of the dungeon prepared, and return with literally everyone to attack the party?
An archipelago might provide a solution - instead of rooms, the party move through islands. Each room would be replaced with a small island. The only doors would be doors to buildings on the islands. The hallways would be stretches of sea.
Random Encounters
Random encounters occurring between the islands mean that random encounters don't need any justification within the 'dungeon' eco-system - they live in the between-world of the sea.
- Sharks! (they do nothing, but skittish players might waste a spell)
- Ship trading food.
- Pirates.
- Griffins
- Wind (roll a sailing check!)
- Dolphins (might help drowning characters, or not)
Map
Of course, most islands have more room than a dungeon room. But they don't need anything more interesting than a single, small structure. And a lighthouse would make sense.
- The forest - anyone stepping beyond here during daylight is spotted by the guardians on island 2.
- Guardians of the islands
...wait, who are these people? Pirates I guess.
- Old fisherman's island (now with a makeshift lighthouse to signal danger to the other pirate-controlled islands).
- Griffin island - and it's egg-laying season!
- Emissaries, where villagers who want to bring food to the pirates come secretly to give food.
- Lighthouse, where the old lighthouse keeper has a list of signals to send to the others to summon aid, communicate a long message, or give the all-clear after a raid.
- Tavern: any fights here really will be overhead by areas 8 and 9.
- The alchemist pirate-captain hatches his schemes and creates magical items.
- Pirates armed with magical scrolls and rings.
The Boat
A big boat would be safe, but a smaller boat can land on an island quietly, in the night, with less fear of being torn apart. Perhaps the local law-enforcement have hired the troupe to travel out on a small boat and take out the islands one-by-one, without alerting the other islands?
Day and Night
Approaching anywhere by day will immediately give the group's presence away. They will have to move through the place within a single night.
Rations & Torches
If someone wanted to lean into the survival elements of rations and such, islands might be stretched apart, so each one takes many hours to sail.
This suggests the opportunity to use Inkscape's ability to embed other images. Each small island might receive a small map, and those smaller maps could each be placed as an Inkscape reference on a larger map.