Tierra Robada Lighthouse Ruins

The Tierra Robada Lighthouse Ruins is the remains of an unnamed lighthouse and an abandoned location in Grand Theft Auto: San Andreas.

Description
The ruins are located near the Bayside Marina in Bayside, Tierra Robada in a small peninsula with steep seaside cliffs on all its sides. At the peak of the cliff side, there is a small, flat, circular structure which resembles the foundation of a lighthouse.

Furthermore, the filename of the ruins,  supports the fact that it is a ruin of a lighthouse. A Skimmer can be found in the beach down the cliff.