Abbey Rock
From The Fifth City Wiki
"A black spit of an island, far from anywhere anyone would want to go. And that's how the Sisterhood likes it. Here stands their fortress-convent. There are bear-traps that look friendlier than this."

Abbey Rock is a tiny island in the Southern Archipelago that harbors the Sisterhood's Island Convent, a small order of feisty nuns apparently established (ironically) by Sinning Jenny.
In addition to Vake-hunters, sailors of the Sunless Sea may visit and explore the island.