When to go tidepooling in California
California has the best-documented rocky shore in the world and a tide calendar that rewards knowing about it. Which months, which hours, and what the protected-area rules mean.
Winter afternoons and summer dawns
California’s tides are mixed semidiurnal: two highs and two lows a day, of unequal size. The lowest tides of the year cluster around the two solstices, and which of them is useful depends entirely on the time of day it lands at.
Around midsummer the extreme lows fall in the early morning, often before six. Around midwinter they fall in the afternoon, from roughly two o’clock to sunset. In California, where a December afternoon is mild and bright, that makes the winter minus tides the ones most people can actually use, and it is why the state’s tidepooling season is generally reckoned to run from about November to March.
The summer lows are lower. They are also at five in the morning. Both facts are worth knowing.
What a good one looks like here
American tables measure from mean lower low water, so a useful California low is a negative number. Anything below about −0.5 ft opens the low shore properly, and the handful of days a year below −1.5 ft uncover ledges that spend the rest of the year underwater.
There are roughly two of these runs a fortnight, following the new and full moon by a day or two. Over a year that is a lot of opportunities, of which perhaps twenty are in daylight, mild and on a weekend.
Why this coast is so rich
Cold water and upwelling. Northerly summer winds push surface water offshore and cold, nutrient-heavy water rises to replace it along the whole coast, which is what feeds the kelp and everything under it. The same mechanism is why the water is bracing in July.
The result on the shore is ochre and bat stars, giant green and aggregating anemones, purple urchins, gooseneck barnacles, chitons the size of a hand in the north, and, for anybody who slows down, a nudibranch fauna good enough to be a hobby in itself.
Marine protected areas, and the rule that follows from them
California runs a statewide network of more than a hundred marine protected areas along its coast, and a large share of the well-known tidepooling shores are inside one. The rules differ area by area: some prohibit taking anything at all, including empty shells and rocks; others permit some fishing and no invertebrate collection.
Given the variation, the honest practical advice is the one on our code page anyway: look, photograph, take nothing, and put every rock back. Do that and you are inside the rules everywhere in the state without needing to know which line you crossed.
Where
The directory covers Californian tide pools from the Oregon border to the Mexican one, each with the species recorded there and a tide chart for the week. A spread of them, north to south: