They worship the Kraken, a giant squid that prows the Trackless Sea and can easily destroy the largest ships.
They are headquartered in the Purple Rocks, at the isles of Trisk and Utheraal, having their main fortress on the former whose facade is shaped like a giant squid. Little was known about the Purple Rocks, but the Kraken cult enveloped the islanders. The Kraken have completely dominated Trisk and they also maintain fortresses on Utheraal to collect tribute.
They also have a base below the city of Yartar, being centered around a huge pool where several giant squid are kept.
The Kraken are allied with the sinister Zhentarim.