Imagine a sentient species that arewith these attributes:
- not very advanced (think primal tribes)
- can breathe underwater
- good swimmers
- feed on seafood (fish, algae)
- live in a high fantasy world with orcs/elves/etc
The specimen are amphibious and can live on surface as well. They have no larval stage, their children are water-breathing from birth. In a Earth-like world, what reasons could they have to build coastal (but not underwater) villages?