Merrow is the term for two seperate groups of isolated seafolk: Kessixian merrows of the Iksandi sea, and Sianic Merrows who live in isolated lakes. Both are sparse enough that they don't form a unified culture, rather blending with the culture of their region or becoming almost legendary by their contact with landfolk.
Kessixian merrows live in pods of 4-6 unrelated seafolk of the same generation, typically splitting off from their parents around age 12, when they reach maturity. Some choose to live among the northern Azohican villages, benefiting from the canal systems and waterside infrastructure. There are some Kessixian merrows that have traveled upstream through the rivers to end up near the tower mountains, or traveled through the marshes and forests on foot to end up in the inland lakes and creeks of southern Azoh.
The merrows of the deep Sianic lakes are isolated to the point that their origin is entirely a mystery. There is often only one merrow in a lake, and they are virtually immortal, provided they are not killed by fearful landfolk. They can grow to be the largest seafolk in the deeper lakes, and their only restriction in size is the size of the lake. It is thought that if one reached a peaceful part of the ocean, they could grow to rival the length of Iksandi warships. They particularly love collecting lost treasures and trading them with landfolk.
There are stories of Sianic merrows taking a liking to land dwellers, visiting them onshore cloaked in mysterious green robes and leaving them pieces of their collection.