Talk:Codex/@comment-24656735-20170120133150/@comment-27655220-20170127012948

Like their Corpus counterparts, these barrels are used to blow up a wall to gain access to a hidden compartment. I have only found them one place:  on one specific tile on the Uranus [Grineer Sealab] Tile. This tile is the one where there is water pouring down the stairs in a narrow side corridor. Follow the water down the stairs until it puddles and you will be sucked down into a hidden room. While in the water, you will see 3 Large Grineer Exploding Barrels floating in the water. Scan them. If you blow them up, they will create a hole in the floor, but will only give access to regular lockers to loot. To get out of the room, you need to leave the water and find a vent access on a side wall.

This tile is not guaranteed to spawn, but occurs on average about once per exterminate or capture mission. Hope it helps.