Hidden caches are large red-orange crates with two yellow lights on each bottom corner. A black and white crate symbol appears above them when you get close, though you have to essentially be on top of them for it to appear.
Having played through about 20 hours of the game, it seems that hidden cache locations are randomized, showing up in (mostly) different spots each time you play through one of Fireteam Elite’s 12 campaign levels.
If you’ve found a cache in one spot, it’s good to check that spot when you run the mission again; crates can appear in the same location, but it’s random when they will. Some locations seem to only appear on certain difficulties, too.
Sometimes, hidden caches are very well hidden, popping up behind random tents or in caves on dead-end paths. Other times, they’re right out in the open, ready for you to find without any effort at all. And other times still, they’re sitting right next to intel locations, letting you kill two birds with one stone.
There are several trophies and achievements either tied to or immensely helped along by finding hidden caches in Aliens: Fireteam Elite.
Keen Eye: Open 50 hidden caches (trophy progress tracks the number of items you’ve received from caches, not the caches themselves). Nukes, Knives, AND Sharp Sticks: Equip three attachments on a single weapon. State of the Art Firepower: Collect one attachment of every type. Ready for Anything: Collect 25 attachments. Express Yourself: Collect 20 emotes. It’s a Cover, Not a Hat: Collect 20 hats. It’s Camouflage on Some Planet: Collect 40 colorways (sprays) Art Gallery: Collect 40 decals. Tower Defense: Use 500 consumables.
It’s worth noting that you keep all of the loot you find from these crates if you abandon the mission or die during a mission. You do not have to finish the mission to keep what you find. This is a good way to grind for attachments and cosmetics.
Of course, you can (and likely will need to) buy attachments, cosmetics, and consumables from SSGT Park at the Armory, but finding some along the way keeps you from having to spend and grind for so many Requisition Credits and Rep Scrip. You can instead spend those on Universal Perks, Kit Perks, and Challenge Cards instead.
And that’s what you need to know about hidden caches in Aliens: Fireteam Elite. Finding their locations off the beaten path not only net you a handful of trophies/achievements, they’ll help you farm weapon parts and consumables, too. For more, tips and tricks, check out our survival guide.