Costly Mistake is a Treasure Hunts type of Quest in The Witcher 3: Wild Hunt. You will obtain it from a Smugglers notes: On a wrecked boat West from Hangman's Alley - Spitfire Bluff. It adds a treasure marker to your map.
"Journal entry goes here"
- ?? xp
- ?? gold
- ?? items
- Video Walkthrough links go here (You must add text)
- Player notes, bugs, and trivia go here