Submerged Hazards of the San Francisco Bay


Sustaining Member
Blogs Author
Consider this thread an invitation to contribute. I have two items to share:

Location 1: Rocks off Marshall Beach

I recently crashed my boat off of Marshall Beach, just outside the Golden Gate. Here's a chart from Navionics. Where the red circle notes the rocks is my best guess. The smaller oval may or may not be the rock I hit. I did recall seeing little rock points on my Navionics on my plotter prior to my bump. I thought I had moved far enough offshore. I still had plenty of room to get inside of the channel marker for the bridge. I thought I was in deep enough water, but I think one of the sub-surface peninsular outcroppings got me.

Marshall Beach Rocks.jpg

Here's a photo of the area, taken around +2 feet of tide today. One can make out some dark bodies lurking under the surface.


I guess my new rule is, once I get east of Baker Beach, I need to stay farther offshore fight the current to get back under the bridge.
Stay at least a half mile off of Marshall Beach.

Location #2: Little Alcatraz

When I brought my boat in to the yard, there was a Beneteau ahead of me on the repair schedule that had struck a rock called "Little Alcatraz." Here's a photo from Wikipedia, with the rock shown at lower left. Little Alcatraz IS SUBMERGED AT HIGH TIDE. Maybe I was told this information in my 101 keelboat class, but I had not really been aware of the rock in my merry novice adventures around the bay.


Per the Navionics chart there is a buoy marked "AZ" (which I think I have approached in the past) outside of Little Alcatraz. I think my operating procedure will henceforth be to always stay South and West of this buoy. Maybe this plan is something that, "Everyone already knows or is supposed to know." If so, good on you, and if not well, consider the risks of a fly-by of Alcatraz.

Little Alcatraz Chart.jpg

So, those are my two examples. If anyone else has ideas for obstacles to look out for, please let me/us know.