Head south from the Abah’s Landing main city. Follow the main road until you spot the Ko Estaraan group boss area. Don’t go down into this area, but rather find higher ground just north from it. I’ve managed to approach it from the east, and the nearby main road. It is easy to reach, once you are at its level. Once you grab it, jump down to the nearby group boss area for that sweet loot.
In the southern part of Hew’s Bane island, just north from the Ko Estaraan group boss.