Sunken Boosters is a DLC Quest in Xenoblade Chronicles 2. It is part of the New Quests Pack 4 of the Expansion Pass. It can be received from Borella on the Gwendle Repair Dock in the Kingdom of Uraya.
After the completion of this quest, Seesaw can be asked to make more Booster Cylinders at any time. These special salvaging cylinders can only be used at Gormott's Lascham Island, and cause Boosters to be salvaged instead of the usual Collectibles and Treasure items.
- "Speak to Seesaw in Torika Alley in Uraya."
- "Get a Booster Cylinder made by Seesaw. He's in Torika Alley in Uraya."
"Thanks to Seesaw's hard work, the Booster Cylinder is complete! Use it to salvage on Lascham Island, Gormott. (DLC Quest)"
As with all quests obtained from the Expansion Pass, the quest will only appear after the corresponding Key Item is collected from the menu.