Each island is its own experiment. On Isabela, giant tortoises weighing over 400 kilograms graze in the misty highlands—these are the galápagos that gave the archipelago its name, and some individuals alive today were born before Darwin's visit. The famous finches hop between cactus and scrub, their beaks shaped by millennia of adaptation: thick ones for cracking seeds, thin ones for probing flowers. At least seventeen species, all descended from a single ancestor that arrived millions of years ago. Darwin didn't actually figure out the finch thing until years later, but the islands get credit anyway.

The Galapagos rose from undersea volcanoes, and several are still active—Isabela's calderas steam on a regular basis. Where lava meets ocean, cold currents from the deep bring nutrients that support ridiculous amounts of marine life. Snorkel off a rocky shore and sea lions will investigate you like you're a new toy. The Galapagos penguin—the only penguin species north of the equator—zips past looking mildly confused about its life choices. Hammerhead sharks school in the deeper waters. The underwater world here is arguably more impressive than the land, which is saying something.

Blue-footed boobies perform their courtship dance by lifting their absurdly blue feet one at a time. (The bluer the feet, the healthier the bird—females are picky about this.) Frigatebirds inflate red throat pouches to the size of basketballs. Marine iguanas sneeze salt. The official rule is to stay two meters from wildlife, but nobody told the wildlife. A mockingbird will land on your head to investigate your hat. A tortoise will walk directly through your campsite. A sea lion will commandeer your beach towel. The animals aren't friendly exactly—they just genuinely don't care that you're there.

Flights from mainland Ecuador land on Baltra or San Cristóbal. From there, boats become your life—week-long cruises that visit different islands each day, or speedboat hops between the inhabited ports. Puerto Ayora on Santa Cruz is the main hub, with about 15,000 people, restaurants, and a research station where you can visit giant tortoises in the breeding program. The National Park controls every cruise itinerary, which sounds restrictive but also means you won't share a beach with a hundred other tourists. Budget at least a week. Two weeks if you can swing it.

The isolation that created the Galapagos also makes it fragile. Introduced rats, goats, and cats have wrecked native species. Lonesome George, the last Pinta Island tortoise, died in 2012—an entire subspecies, gone. But conservation efforts have scored real wins. Islands cleared of invasive species are recovering. Tortoises bred in captivity now wander their ancestral turf. The $200 park entrance fee (yes, really) helps fund the work. The Galapagos is a reminder that some places require active protection, and that the animals who never learned to fear humans are counting on those humans to be responsible.