There are 7 red chests in the Trash Coast. White chest which is only accessible after killing the Rakk Hive during the Another Piece Of The Puzzle mission contains the third Vault Key Piece and a large quantity of cash, but no weapons. This chest is found empty on further visits.
Location 1 (Red Chest)
On the small island northeast of the vendors, on the way to the Rakk Hive. It is guarded by several groups of spiderants.
Location 2 (Red Chest)
In a small bandit camp located in the central southern part of the map. It is found next to the broken Claptrap.
Location 3 (Red Chest)
At the southernmost part of the map, overlooking the ocean and is guarded by a large number of spiderants.
Location 4 (Red Chest)
Between huts in a small bandit camp located in the central western part of the map. This camp overlooks the area where King Aracobb is found.
Location 5 (Red Chest)
In the same camp as the chest #5. Most times it spawns to the left of chest #5 but can randomly spawn in 5 different locations; see the map.
Location 6 (Red Chest)
Location 7 (Red Chest)
Sits just outside the southern edge of a cage where Scrappy was held. This crate can be looted from within the cage.