You'll have to wait to swim further past that big ole boat in Act 3 when it's pulled out of harbor... so don't worry for now.
Yes, the code to the door will require a bit of thought. Do you remember where you've seen those symbols before? To use as the key for a substitution cypher?
The door code solved 😎 I believe I’stuck because of a bug now though. I used Trophy near the statue inside the house. A strange pop-up appeared on the right-down, it looked like an ID card or something. Then I opened inventory and saw Trophy (held), used it again and it just disappeared from the inventory along with the pop-up 🥲 After that the inventory doesn’t let pick up the second item, as there are two items in it. Like I can’t carry two ID cards anymore, for example. Then I tried to get the Trophy again, and I could take it as the second item. But then I dropped Wetsuit and can’t take the second item again having only Trophy...
Update: It’s definitely a bug. I took the Trophy again and did the same thing. It happened again and now my inventory is empty (except Radio) and I can’t pick up anything :( Restoring from a save point doesn’t help - the inventory stays the same. Had to restart the game from the very beginning…