Well, from what I gathered we probably can forget allying with the fish people. The Siren or Mermaid might be more inclined.
Oh, and giving that the fish guy tried to rob us, I'd say we take his javelin. It's probably not very useful, but who knows?
After we can let him go, but not before giving him a stern warning to leave us alone. I doubt he will listen but it's worth a try.
And yup let's go to the reef.
If I have my lore right, gathering in a lantern spot is a safe affair, but the only one who can swim is Goma.
I'm a bit torn with sending her down there alone. On one hand we might get that clam from there but on the other hand there will be at least some time where Goma is seperated from the group.
If anyone wants to reread the relevant chapters to gathering spots:
https://chyoa.com/chapter/Muma.1018893
https://chyoa.com/chapter/The-Lantern's-Guiding-Light.1020501
Personally, I lean towards leaving the gathering spot be for now and continue to the new island.
Oh, and the path towards said new island looks perfect for an ambush. So everybody remain vigilant while crossing over. Let's keep Goma and Isalia in the middle.
Also updated map