Both treasures are inside the opening on the south side; one is in the southeast corner and the other is in the southwest. Find the hole on the west side. Use it to stealthily drop in from above. This gives you access to the commander, who roams in and out of this area. A Parkour Up device is at that entrance. Use it for a quick getaway when necessary. The captain sticks to the upper level above this interior. Use the wooden fence to hide entry and exit.