Destiny 2's latest Exotic hand-cannon, Lumina, is a beautiful weapon with an appropriately taxing questline. The Sinking Docks is one of the locations in which a particular hidden treasure spawns - one that is necessary for the completion of the Lumina quest.
Now, in order to find the hidden treasure in Sinking Docks, you're first going to need to know where this particular Sector is in the first place, and where to look for said chest, too. Find all of this information - and more - just down below.
Lumina Sinking Docks Treasure
The Sinking Docks dungeon is a small sector of the map located on Titan, and you'll be happy to hear that its appropriate 'hidden treasure' isn't such a bother to find and loot after all. First things first, go to Titan, and transmat your Guardian to the Siren's Watch rig. When there, keep the map showcased above in mind, and head toward Sinking Docks.
At the Sinking Docks, you're looking for a wrecked set of platforms leading below the main rig, which you want to descend. The chest in question will be to the right after you drop to the lowest platform, just hidden behind a wall with the mob-spawning door.
We hope this helps you in getting the Lumina! You're not done with the quest yet, after you get this chest, but you will be one step closer to the prize. If your quest takes you to Spine of Keres instead, we've got you covered.