Summons to Death - Tang Ching (1967) - Basalt Island, Port Shelter

The film finishes off where it started, in Port Shelter. The sea cave that the pair go through in order to reach the treasure is located on the south east side of Basalt island - one of Port Shelter's easternmost islands. GoogleEarth has a single image that shows the cave here from the same angle that can be seen in the lower image.