Veni Vidi Vigo
Back to Act III – Wild Hunt
For this quest you must bring Fringilla Vigo off the Nilfgaardian flahship. You’ll need to swim over to the flagship in the evening and avoid all of the spotlights from the other ships. If you are discovered while swimming the soldiers will become hostile.
Once you reach the flagship find the side with the anchor. One of the soldiers will recognize you and let you climb onboard.
Geralt will ask Emhyr to release Fringilla as she’s needed with the fight against the Wild Hunt. She’ll teleport you back to Kaer Trolde Harbor and the quest will be complete.