The three islands are rocky and marked with only small pockets of trees and jungle. Much of the land is steep, volcanic peaks with sheer cliff faces pockmarked with caves, caverns, and shelves. It was a violently-made series of islands, created from volcanic activity from under the ocean. They are not very welcoming-looking.
With little safe land to exploit for resources, there is very little reason for ships to stop there. The islands are mostly uninhabited, but are rumored to hold harpies, blood hawks, and a large roc. The Revelry uses them for storage, meetings, and ambushes.
One of the lost temples of Uk'otoa was located beneath the sea at the center of the three islands, guarded by multiple sea spawn, chuul, and a deep scion. Fjord replaced its Cloven Crystal and the seal is now unlocked. This appeared to trigger the destruction of the underwater temple itself.
"A Storm of Memories" (2x46)
The Mighty Nein anchored the Ball-Eater in the center of the three islands. Frumpkin (as an octopus) located an underwater tower and the party descended there (using Underwater Breathing), following Fjord's vision of the location of the second temple of Uk'otoa. The tower did indeed appear to be a temple, and the party defeated five sea spawn guarding it.
"The Second Seal" (2x47)
After winning a fight within the underwater temple, Fjord asked the rest of the party to leave while he successfully inserted the Cloven Crystal on the Sword of Fathoms into an indentation there. The party escaped to their ship but were attacked by a pirate ship hiding in a cove. Caduceus sank it using Control Water and they left the survivors on one of the islands.