Red Rock Island, for sale at redrockisland.homestead.com.
From the Light-House Board Annual Report of 1904:
Red Rock, upper part of San Francisco Bay, California.—This rock is an island about 169 feet high, and contains about 7½ acres. It stands near the eastern shore of the bay, 9½ miles above Market street, San Francisco, and is passed close to by vessels bound for Port Costa, Benicia, Mare Island, and the rivers emptying into Suisun Bay.From the Annual Report of 1922 (note how much less money was needed for an unmanned, electric light):
It is believed that with the establishment of a light at Southampton Shoal, Red Rock would be a better place than Quarry Point for a light and fog-signal. With this station vessels bound up the bay could make Southampton Shoal, giving Quarry Point, Angel Island, a wide berth, and from thence shape their course to Red Rock, on either side or which they could pass. This rock, or island, formerly known as Molate Island, is a military reservation, but does not enter into the adopted project for the defenses of San Francisco, and hence no difficulty is expected in obtaining authority to occupy it for light-house purposes.
It is estimated that the cost of a light and fog-signal station at Red Rock will be $30,000, and the Board recommends that an appropriation for that amount be made therefor.
Red Rock Light and Fog Signal, Calif.—Establishing a light and fog signal on Red Rock in the northern part of San Francisco Bay, Calif., $14,000.The lighthouse was never built, though Red Rock remained government property for decades. Now the island is for sale. See more of its history (and the Realtor's website) at redrockisland.homestead.com.
Note.—Red Rock is a bold, rocky island in the northern part of San Francisco Bay, rising to a height of 159 feet, with deep water close to its shores. It lies in the path of the very heavy up-bay and up-river traffic, as well as in the path of all craft proceeding to and from the Mare Island Navy Yard, and is also directly in the path of the passenger and automobile ferry steamers plying between Castro Point and Point San Quentin. Requests have been received from the masters of river steamers, of oil tankers, and others to suitably mark this island with a fog signal and light. It is proposed to establish a compressed-air diaphone on the south end of the island and to establish a sixth-order flashing electric light of about 3,200 candlepower.