Sutro Baths and Land's End are two in one here! And the beach is right there too.
Not exciting enough to do as a stand alone activity but check it out before starting the Lands End hike!
Bring a flashlight and go when there's a full moon, you can park along the road at night
On a clear night...beers and food make for an amazing date
Bring a jacket, the fog starts rolling in during the late afternoon, and combined with the seabreeze, it gets very chilly.
Bring a flashlight and go into the cave
Camera + jacket
Hauntingly pretty part of town. Remnants of the old city that harken back to the early 1900s. Very cool seeing the ruins and the ocean and imagining what it must've been like a century ago.