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.
Sand Kingdom Moons - Super Mario Odyssey Power Moons