It’s obtainable on the route of “Retrospective Runaround” jumping puzzle. The start of this route is close to the Drydock Grotto Waypoint. As you are about to jump over a small gap between two large boulders, that almost form a bridge, look down. Down there is Sand Dune Caverns POI area. It’s a long way down, but while falling down you’ll discover the POI. Luckily, a skritt will revive you down there and you can enjoy the surroundings.