I thought most people would know about this by now but I haven't seen any threads on it yet. I found this chest about 30 mins after the raid dropped last night . After the part where you have to use the tomb ships to jump across the chasm, continue on until you see the forcefield that requires you to stand on the left and right plate to deactivate. Get two people on the plates as this opens the hidden door. Then the rest of your team must jump on the ship and before you pass through the forcefield. Jump off onto the small ledge sticking out the wall. Run up this and there will be a small opening with a door just above you which when you enter, has a chest inside. Ill try and post a video If anyone wants one