Linebeck Island is located near the center of the Millennio Sandbar within the Lanayru Wetlands. It connects to Goponga Island to the south and Mercay Island (Breath of the Wild) to north through small wooden bridges.
The island has a large tree growing, of which it has an Acorn hanging down from it. Link can shoot it with an arrow to get a Korok Seed. A second Korok can be found to the west, halfway between Linebeck Island and Zauz Island. Link can catch the sparking flowers to get the Korok Seed. There is one treasure chest near the island, partially buried in the water just southwest of the main tree. Link can pull it up with Magnesis to find a Purple Rupee.
Nearby Korok Seeds
Catch the fairy lights.
Shoot the hanging acorn.