A rusted windmill watches over Scorpion Ranch on Santa Cruz Island, a reminder of man's impact on even our wildest places. It is but one of an array of archaeological and historic sites in this national park.

But the Channel Islands are still defined more by the sea and the wind than by anything else. On land, the dry grasses and shrubs remain in motion, mimicking the whitecapped water of the Santa Barbara Channel that separates the islands from the mainland. These waters contain a diversity of life matched by few places.

Although they make up one of America's less visited national parks, the Channel Islands offer plenty of reasons to keep visitors coming back. Opportunities for sea kayaking and hiking are numerous, you'll find plants and animals that live nowhere else, and archaeological remains serve as reminders of long-vanished cultures. It's also a draw for underwater explorers from all over -- twice as many people come here to explore the waters around the islands as ever set foot on the shore.

Channel Islands National Park encompasses the five northernmost islands of an eight-island chain: Santa Barbara, Anacapa, Santa Cruz, Santa Rosa, and San Miguel. (The park does not include Santa Catalina, San Clemente, or San Nicolas.) Not limited to the islands themselves, the park also encompasses 1 nautical mile of ocean around each island, and the 6 nautical miles around each island have been designated a national marine sanctuary. The smallest of the park's islands, tiny Santa Barbara, lives a solitary existence off by itself. The four northern islands cluster in a 40-mile-long chain. During the last ice age, before the continental ice sheets melted, driving up the level of the sea, these islands were connected in one huge island that geologists now call Santa Rosae.

Although it was once theorized that the Channel Islands broke off the California coast some 600,000 years ago, geologists now believe that the islands were never connected to the mainland, ultimately owing their origins to underwater volcanic activity.