This was the first refuge that the fleeing drow of Drakkar founded, and their last stand against their former slaves. They ultimately failed in holding this vital fortress port.
Drakkar did not have its vengeance though. When the city finally fell, there were far too few drow left in the city. Most of the nobles and retainers had disappeared, and the defenders at the end were mostly slave warriors and low caste drow. Its like the drow disappeared into the ground.
This port is more important for Cherembryl as a deep water military port than any possible use for trade. So much of the city has been left in the same state as it was when it was sacked. The ruins have had a number of unsavory squatters move in, but since they haven’t bothered the naval base they are largely ignored.
Port Perilous’s Golarion equivalent is Shadow Lodge.