Although the name suggest it is hidden in some kind of a shipwreck cove, don’t search for signs of any ships. If you follow the coastline you can spot it from the distance. There is a small waterfall just next to it, but this is not that big of a landmark, as there are many of them in the area. If you head toward the coast, downhill from the nearby public dungeon, you’ll stumble upon it without a problem.
Sand Kingdom Moons - Super Mario Odyssey Power Moons