The Season of Plunder is off to a strong start in Destiny 2, with the Guardian, the Drifter, Eido, Misraaks, and the Spider going on the hunt. Despite Eramis rallying a crew around her and embarking in search of ancient treasures, the forces of Light aren't willing to let her get away. Part of this quest involves a literal treasure hunt with the Guardian needing to track down treasure Coordinates for additional booty.
Where to find Treasure Coordinates in Destiny 2
Treasure Coordinates are awarded upon completing Strikes, Crucible matches, Gambit matches, Lost Sectors, and other activities. Completion of said activities will award anywhere between 15 to 40 Treasure Coordinates. However, Guardians can boost the drop rate of Treasure Coordinates by wearing Ketchkiller armor pieces. Each piece (excluding class items) nets an additional 5%, stacking at 20%.
The Treasure Coordinates are used when doing the Expedition activity and will uncover an extra chest of loot at the end. Depending on the Map Fragments used, there will be different rewards like more glimmer, Seasonal Armor, and more. It's a convenient way to passively increase your loot as the Treasure Coordinates are gained while completing other activities, and the Expeditions are a part of the seasonal quest line. As such, make sure you spend them!
For more Destiny 2 goodies, check out Destiny 2 Dictionary – Current Vocabulary and Slang for Guardians on Pro Game Guides.