Caliche Forest Trail

Overview

This is San Miguel Island’s showstopper: a ranger-guided, out-and-back walk from the Cuyler Harbor area to the otherworldly Caliche Forest. Expect roughly 5 miles total (round-trip) over exposed, uneven terrain with moderate climbing. Independent access is not allowed—hikes run only with a ranger due to the island’s former bombing-range history and the risk of unexploded ordnance. You must stay with the group.

What You’ll See

The payoff is a rare landscape of fossilized root and trunk casts—ghostly molds of ancient trees (likely pine and cypress) preserved in caliche and revealed by wind erosion. Some casts are impressively large, including a log-scale trunk cast more than 2.5 feet thick and 30 feet long. Underfoot, you’ll cross caliche hardpan, sandy stretches, and windswept ridges with broad Pacific views. Keep an eye out for island foxes and seabirds; in spring, wildflowers dot the open slopes.

Geology & Backstory

During the last ice age, wind-blown sands buried living vegetation. Over time, calcium carbonate from shell fragments leached through the soil, cementing sands into caliche and filling voids left by decayed roots and trunks—creating the hardened casts you see today. Later livestock grazing stripped protective topsoil, and relentless winds further exposed this “fossil forest.” It’s one of the most unusual geologic sights in the park.

Logistics & Rules

• Ranger-led only; do not attempt this route alone. You’ll typically start after boats arrive at Cuyler Harbor. A permit/waiver and strict adherence to ranger instructions are required.
• Surfaces are sandy and sometimes slick on the hardpan; there’s no shade and winds can be strong. Bring sturdy footwear, sun protection, and plenty of water (there’s no potable water on the route).
• No pets. Camping is limited to the designated campground near Cuyler Harbor (not on the trail).

Best Time to Hike

Spring and fall usually offer the best mix of milder temperatures, clearer air, and seasonal wildflowers, with less wind and fog than the height of summer or winter. Regardless of season, prepare for changeable coastal weather and steady wind.

Is It Worth It?

If you’re into geology, paleobotany, or just love a truly singular landscape, absolutely. The hike is exposed and can feel tough, but the Caliche Forest’s surreal casts and the island’s wild, remote feel make this one of the most distinctive hikes in the park. If you want a gentler day, consider sticking closer to Cuyler Harbor’s beaches and bluffs, but for a guided adventure with a genuine “nowhere-else” payoff, this is the one.