Saro

Saro is a planet just beyond the edge of the Mathrin cluster. It started its life as a pirate haven, and now is home to a thriving, extremely malevolent underworld.
Brackish swamps cover a large part of what landmass there is, and the oceans are almost as bad, with poor weather on the whole.

SPOILERS FOLLOW

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Blood Cove on Saro was the location where Vania was said to be held. However she was not actually there and the fortress was a trap in which Evelyn was seriously injured. In revenge, Fya wished the island destroyed. That resulted in a rogue planet being nudged out of orbit and colliding with Saro, with Blood Cove being the point of impact.