This Tuesday at 5:37 pm there is a minus tide, in fact it's one of the lowest of the year. To read the 2013 SF Bay tide tables, click here.
There are several fun things to do around a low tide: walking underneath the Cliff House and climbing on the rock in front of Sutro Baths; braving the climb to the hot springs hiding in the sand near Steep Ravine (best for grown ups); tide pooling at Fitzgerald Marine Reserve in Moss Beach. During low tide, the National Park Service suggests you walk between China and Baker Beaches to admire the star fish and sea anemones clinging to the cliffs.
Any other low tide outings to recommend?