The island of Espiritu Santo is isolated, in the very fact that it is an island, but it also sits in between two landmasses; the Baja peninsula and the Mexican mainland. Combined with the fact that the island sits just north of the Tropic of Cancer, Espiritu Santo is ecologically rich. Recently, the Nature Conservancy and other conservation groups helped the Mexican government purchase the island in an attempt to maintain its ecological integrity. It is now a United Nations Biosphere Reserve and a Flora and Fauna Protection Area.

The island is home to some very unique wildlife, including the blacktailed jack rabbit, a cactus endemic only on Espiritu Santo, the round-tailed ground squirrel, blue footed boobies, two snake species endemic to the island, a ring-tailed cat known locally as the Babisuri, and huge colonies of sea lions.

Because of all these facts, Isla Espiritu Santo and the islands that dot Mexico's Sea of Cortez are valued and studied by a field called island biogeography. Biogeography is a science that concerns itself with the distribution of species; why they exist in one place and not another. And also, to explain why species' may have existed in a place, and why they exist there no longer. Island biogeography, then, is this same science focused on islands. Why this science is important is probably best described by science author David Quammen, in his well-known island biogeography piece called Song of the Dodo. "Many of the world's gaudiest life forms," he writes, "both plant and animal, occur on islands."

Small ecosystems compound the effect of evolution, so they make great laboratories of the bizarre.