Sea Elf

Sea Elves live on large ships and other seafaring vessels.
They are the only elves who know the waters well enough to sail with minimal risk so most tribes, and even sky cities if needed will ask the Sea Elves to transport people, supplies, etc. Which the sea elves do as a line of mercenary work.
The sea elves are ruled over by a council of 5 Admirals, one for each ocean of Kemnór, and each named after each ocean they tend to, who occasionally meet to discuss large events/decisions by docking their fleets together, essentially creating massive floating cities that can do trade, etc.
Sea elves of course can dive deep underwater, and it's rumoured they have cities below the waves, but no one but a sea elf has ever seen one or been to one. So the landlubbers believe the above more likely to be true.