Treasures of the Mayan civilization?
The game world is huge. And that’s great . However, islands and reefs are only part of the available world. The depths between the islands are empty. I think they can be used (at least partially).
For example: put 15th-century sailing ships (wreck) for exploration in several places. To find: gold items (e.g. a lighter ) . Gold product\s of the Mayan civilization (only for decoration or as indestructible tools).
Coordinates of the location of the treasure (treasures): hidden on an island, in the form of a clue (some inscription, poem, map, riddle). Treasures difficult to locate. Then the exploration of the islands takes on a new meaning .
Breath boost and a few air tanks…