There are about fifty blocks full of surveyed and zoned "water lots" in South Basin, southeastern San Francisco -- property which is presently part of the San Francisco Bay. See these blocks on Zillow; 5000 square feet of bay appears to change hands for a few hundred dollars.
Water lots in the port section of the city were once the subject of speculation and political drama. The city government was badly indebted and not supposed to draw or sell off water lots, but did so. Much of today's downtown is land that was once water lots.
On the southern waterfront near the present county line, quite a few city blocks of South Basin were never filled in. Maybe it had somehow to do with the adjacent naval shipyard at Hunter's Point or the establishment of today's Candlestick Point State Recreation Area.
When were these blocks and lots defined?