Lichii'dass Reef

The largest settlement is a relatively shallow part of the southern golf. The city is spread around the reef's submarine volcano, protecting the inhabitant fishes from invasive species and Morkoths. They will eat a few inhabitant fishes during times of hunger, but prefer the meat of well hunted meat. This settlement doesn't have an outgrowing sentiment like the other merrow as they consider upholding tradition a higher priority. They are more xenophobic to outsiders and will attack ships that sail close to their reef, later to be traded to Xirnii.

Rewreka

The hydrothermal trench of Rewreka has a special defensive position against most large predators like dragon turtles and krakens. The Merrow here are calm and welcome most creatures for trade and festivities¹. They are expansionists that don't mind harvesting oil and nodules to shower visitors in as long as it uphold their pact with the druidic circles. In recent decenia, they are starting to dig holes into the underdark to mine without angering the circles, but their land-based battles are difficult against the underdarks hostile predators.

Rewreka Organ¹

Merrow know music on many levels, as inspiration and communication. They invented a version of the hydraulophone, an underwater organ that uses two whale jaws to push pressure through small holes making a long deep drone. The sound is able to carry as far as 2 thousand miles, which is perfectly receivable to the other settlements.
Smaller version can be as small as an ocarina or bagpipes