A short while later I dinghied ashore to hike up the hillside while Mark and Christine set out in their inflatable kayak to look at the colorful starfish and decide whether conditions were good for scuba diving. Santa Cruz’s hills are steep, and the vegetation on the ridges is mostly knee- or thigh-high. About 20 inches of rain a year falls on the island, nearly all of it in the winter, and the plants range from desert succulents like the prickly pear and cholla cactuses, to manzanita and sticky monkey.

From my vantage point a thousand feet up, Blue Moon looked like a tiny boat resting in a very small pocket of water. The Channel Islands are uniquely big, rugged and wild, making Washington’s San Juans, the islands of Maine and the Florida Keys seem tame by comparison. Three of the four main islands have been inhabited, first by the Chumash Indians and later by ranchers and the military, but that’s it.

From high on the hillside overlooking Little Lady’s, the only sign of human intrusion was a single brass cartridge shell from a small-caliber rifle, the kind a rancher might use for shooting “varmints.” The Nature Conservancy, which owns the western 76 percent of Santa Cruz, and the National Park Service, which controls the rest of the islands, once hired a New Zealand firm called Prohunt to eradicate the pigs that were introduced as farm animals in the mid-1800s and later went feral. Sheep were also once a problem and have repeatedly razed the natural pastures on the island. Fennel, one of California’s more insidious and tenacious weeds, was introduced by early farmers and remains a problem to this day. Nonetheless, the western portion of Santa Cruz, in particular, still looks as wild as can be. Powerboat squadrons on Memorial Day weekends aside, it makes for a close approximation of wilderness.

We’d been so isolated in our own little pocket that we’d almost forgotten about the outside world. Making our way back east, past Pelican Bay, we stayed in close to the shore so we could better appreciate the contours of the island’s cliffs and bays. Picnickers were anchored in some of the little nooks, and kayakers were clustered around the docks where the ferry from the mainland discharges passengers. Toward the eastern end of Santa Cruz there were buildings, road cuts, fences and some old sheep-shorn pastures, now uniformly covered with grass. It seemed quite bucolic compared to the wilderness of Little Lady’s. At the end of the day we joined a dozen boats in Little Scorpion anchorage.

On Monday it took only a few hours of easy sailing on a broad reach to return to the mainland, and shortly after tying up in Ventura Harbor we were airborne in the Mohlers’ little Piper Saratoga. We passed over the harbor and out above the Santa Barbara Channel. Through one window we could see the highways, parking lots and rooftops of Southern California. Through the other were the rugged hills of Santa Cruz. It’s remarkable to realize that these two completely distinct worlds are separated by only 20 miles of water.