During the lowest tides of the year (check the tide book for current year - should be 1.5 and lower - about 4-5 times per year, always at the winter and summer solstices and then a few other times) drive toward Stinson Beach over the top of Mt. Tam.
When you get to Highway 1 at Stinson, turn south (left) and drive ~1 mile. Look for a driveway on your right that is labeled "Steep Ravine". Park your car somewhere on Highway 1 near this driveway. Walk down the driveway all the way to the bottom, then wind your way through the cabins to the beach to the north.
If you time your arrival for the peak of the low tide, all you have to do is walk along the beach until you see many naked bodies piled into a collection of hand-built hot pools. If you arrive early, you'll have to scramble along the rocks at the bottom of the cliffs (because the beach won't be exposed yet). If you're very resourceful, you'll smell the sulfur and know to look for buckets to start digging the sand out. If not, just wait for a few minutes and the regulars will be there to start the process. Don't worry about the regulars' attitudes about first timers - just start helping out with the digging. (Clothing is optional!)
This is an exsperance! There are a few hot springs along the beach which you have to dig a hole for. I saw mostly families. There is one in the rocks. mostly unclothed locals.
