Overview
The Black Widow is a Blood and Wine treasure hunt in Sansretour Marsh, on the Sansretour River far west of Flovive.
Walkthrough
Three drowners are feeding on a corpse at the hidden treasure spot. Kill them, then take the small key and the letter to Pascal Pélissier and read it. Swim south to the marked area, where more drowners wait; a Killer Whale potion helps with the many hard-to-reach containers. The treasure lies in the broken section of the ship near the western edge of the search area, beneath the part sticking out of the water.