“Mer-ky Depths” is a side quest in Hogwarts Legacy given by Nerida Roberts at the Boathouse Floo Flame.
For this quest, players will need to navigate to a nearby underwater cave and use Lumos to move the moths to the door and solve the puzzle.
In this guide, I will explain how to start and complete the “Mer-ky Depths” quest in Hogwarts Legacy.
For more quest guides, consider checking out our article on how to complete the “Cache in the Castle” quest.
How to Start Mer-ky Depths
Players can start “Mer-ky Depths” by visiting the boathouse Floo Flame located in the Great Hall. From there, Nerida Roberts will be waiting right outside the door, next to the lake, or there will be a yellow circle where players can wait for her.
This quest can be started early in the game and will be available even after players progress through the story and the seasons change.
After talking with Nerida, the quest will begin and players will be tasked with entering an underwater cave nearby.
Merky Depths Quest Guide in Hogwarts Legacy
For the first part of the quest, start swimming right behind Nerida and you’ll find the entrance to the underwater cave near the rocks in the water.
Interact with the entrance and you’ll get teleported inside where you’ll have to solve a puzzle.
Specifically, there will be a door in front of you with three moth slots. All around the cave entrance, there will be three moths on pedestals, hidden behind cobwebs.
Using Incendio/Confringo to burn the cobwebs, and then use Lumos to get the moth to follow you. Bring the moth to the door and unequip Lumos. This will cause it to enter the slot in the door.
Repeat this process with all three moths and the door will unlock. Behind the door, there will be one chest, which will include a mermish artefact. Bring this back to Nerida in the boathouse to complete the quest and gain your rewards, which is an outfit.
Wrapping up
To summarize, players can complete the “Mer-ky Depths” quest by interacting with Nerida in the boathouse, visiting the nearby underwater cave, and solving the puzzle by guiding the moths to the door.
If you want to learn every spell in the game, consider checking out our guide on how to learn the three Unforgivable Curses. They are hidden behind sidequests and players can easily miss them if they’re not attentive to detail.
Did you have trouble solving the puzzle in this quest? Have you been struggling with any other main or side quests? Let us know in the comments below.
He has a Master’s Degree in Philosophy, which allows him to always come up with a fresh approach to solving in-game puzzles and challenges, but also to create content that’s to the point, clean and easy to follow.
- Arena of Valor Tier List [Updated for 2026] - January 15, 2026
- Best RPGs with Romance and Relationship Options (2026 Update) - January 13, 2026
- Best Boxing Games for Xbox: Play Them in 2026! - January 6, 2026