In the Forgotten Realms, Umberlee is the vengeful and sadistic goddess of storms and the ocean. Players can visit one of her temples in Baldur's Gate 3 by heading south from the Gray Harbor waypoint, and when the party shows up they're mourning the loss of one of their sisters.
The party can take on the quest "Avenge the Drowned" by speaking to Flood Tide Allandra Grey, who leads the chant over her fallen sister's body. However, the target of her wrath is well hidden, and he's also essential to two other very important quests. Players of Baldur's Gate 3 can complete all three quests in a single playthrough, but they must be very careful about the order of their actions.
How to Start "Avenge the Drowned"
Umberlee's temple is open to the public, so simply head south from the Gray Harbor waypoint and walk straight up to the group of women singing over their fallen sister. The person to speak to is Allandra Grey, who stands with her back to the entrance.
Allandra wants revenge, and so when she asks for tribute she'll accept "I've brought my weapon to help avenge her death." She'll explain that her fellow priestess died when she collided with a "metal monster," which is to say a submersible. Allandra will then ask the party to kill the monster's master, and the quest will appear in the journal.
Where to Find the Submersible
To locate the submersible, head over to Flymm Cargo. Players can find this warehouse east across the harbor from the Gray Harbor waypoint. The door in is locked and forbidden, but the party can get in by jumping onto the roof from a walkway on the east side of the building and then jumping down to a staircase on the south side. The doors here are also forbidden, but no one can see the party from this angle.
Inside the warehouse is a small pack of wargs, massive wolf-like beasts that will attack the party on sight. Fortunately, they aren't much of a challenge to an Act 3 party. Once the wargs are down, go to the northwest corner of the warehouse and start moving boxes. There's a large hatch hidden beneath them.
Once in the basement, go straight ahead from the ladder and through the door to find a hidden submersible bay. A dwarf here named Redhammer the Deviser is the submersible's creator and captain.
This is where timing becomes important. Redhammer and the submersible are how the party reach the Iron Throne, an underwater prison created by Gortash. Players must visit the Iron Throne for the quests "Save the Gondians" and "Rescue the Grand Duke." If the party convinces Redhammer to pilot his vessel down to the Iron Throne, he'll enter his submersible and become impossible to target. However, after visiting the Iron Throne, he'll reappear in the bay. Just make sure to perform a long rest so all the Gondian survivors won't be around during the assassination.
Here's the other way timing comes into play: if the party visits the Iron Throne first, the quest "Avenge the Drowned" will be unavailable. Even though Redhammer is still alive and accessible, players can't volunteer to avenge the Umberlee priestess if he already helped them reach the underwater prison.
Fortunately, players don't need Redhammer alive to visit the Iron Throne. The party only needs to be aware of the existence of the prison, and they can get that information from earlier in the conversation with Redhammer or from the Gondian workers in the Steel Watch Foundry. If they know the Iron Throne is down below, the party can pilot the submersible themselves.
With all of this in mind, the best order of operations is:
- Speak to Allandra Grey and start the quest "Avenge the Drowned."
- Find Redhammer under Flymm Cargo and convince him to mention the Iron Throne.
- End the conversation immediately after getting the info.
- Kill Redhammer.
- Use the submersible hatch to reach the Iron Throne and rescue the prisoners.
- Return to Allandra and complete the quest.
The reward for this quest is the 
Wavemother's Robe
. This set of clothes provides +1 Armor Class, Resistance to Cold and Fire damage, access to the spell 
Create or Destroy Water
, and +1d4 hit points each time the wearer starts their turn standing in water. This ability works outside of combat, and it works with water created by throwing a bottle or casting the spell.
Baldur's Gate 3 is available now on macOS, PC, and is coming to PS5 on September 6.
