Sandy Bay, also called Sunset Beach, is the small cove beside Devil's Tear. It is less about swimming than atmosphere: waves rolling into the bay, a few beach places set back from the sand, and a good west-facing position for late light.
The sea can be rough, so do not assume the water is safe just because the beach looks calm. Sandy Bay works best as a sunset stop after visiting Devil's Tear and Dream Beach, or as a quiet place to sit with a drink while the day-trip traffic leaves.