The isolation of the Channel Islands has allowed a diverse array of life to develop and evolve, prompting some biologists to dub the islands the "North American Galápagos." Most of the differences from mainland species are in size, shape, or color variation. Perhaps the most curious of the islands' former inhabitants was the pygmy mammoth, only 4 to 6 feet tall, which roamed over Santa Rosae during the Pleistocene era -- fossilized remains have been found on San Miguel, Santa Cruz, and Santa Rosa.

Other island species have survived. Like the mammoth, the Santa Cruz gopher snake, island spotted skunk, and endangered island fox (two of the islands' three endemic mammal species -- the other is the deer mouse) have all evolved to be smaller than their mainland relatives. At just 4 pounds, the island fox is the smallest fox species in North America. Like Darwin's finches in the Galápagos, the islands' native birds also show marked adaptation: The Santa Cruz Island scrub jay, for instance, displays "gigantism" -- it is one-third larger than mainland jays.

But the diversity of animal life is outdone by the array of native plant life. One of the most spectacular of the islands' plants is the yellow coreopsis, or tree sunflower, which grows on all five islands (as well as the mainland). Other species of plants live nowhere else on Earth -- the islands support a number of endemic varieties of plants. Santa Rosa's endemic Torrey pine population dates from the Pleistocene era, though a remnant mainland subspecies survives at Torrey Pines State Reserve, north of La Jolla, California.

Marine life around the islands easily wins the diversity award. The islands are the meeting point of two distinct marine ecosystems: the cold, nutrient-rich waters of Northern California and the warmer, clearer currents of Baja California. Everything from microscopic plankton to the largest creature ever to live on Earth, the blue whale, calls these waters home. Orcas and great white sharks, anemone and abalone, lobsters and starfish, plus dozens of varieties of fish, live in the tide pools, kelp forests, and waters surrounding the islands. Six varieties of seal and sea lions beach themselves on San Miguel, four of which breed here, making it one of the largest seal and sea lion breeding colonies in the United States. The islands are also the most important seabird nesting area in Southern California.

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