Treasure: Route BC

San Cristobal's airport sits at the edge of Puerto Baquerizo Moreno, a five-minute drive from the town center, so this is usually your first taste of the islands rather than a standalone excursion. Sea lions and marine iguanas are known to rest right next to the runway here, an unscripted welcome few airports can match. From the terminal, a short transfer takes you down to the pier for a panga ride out to your ship.

Set in the moist highlands of San Cristobal, this reserve, also known as La Galapaguera, is dedicated to restoring the island's threatened tortoise population. A walk through the grounds takes you past tortoises at every life stage, from hatchlings to full-grown adults, part of the same breeding and reintroduction effort.

A short landing on one of the most beautiful beaches in the islands brings you into a resident colony of Galapagos sea lions, sprawled across the white sand. Between August and November you may also spot pups nursing nearby. This is one of the only places to see the Espanola mockingbird, found nowhere else on Earth and famously unbothered by visitors. After time on the beach, a relaxed snorkel just offshore is a good way to close out the visit, with spotted eagle rays often gliding beneath the surface.

One of the few places in the islands where human history takes center stage over wildlife. In 1793, a whaling captain installed a wooden barrel here as an informal mailbox, and the tradition has never stopped: you're welcome to leave a postcard without a stamp, and to sort through what's already inside for anything addressed near your own home to hand-deliver in person. After a wet landing on the sandy beach, a short walk brings you to the barrel, then on to a lava tube you can climb down into by ladder. It is one of the most memorable traditions anywhere in the islands.

Formed by geological uplift rather than volcanic activity, Santa Fe is unusually flat for a Galapagos island, and it's the only place on Earth with its own endemic subspecies of land iguana. After landing in clear, turquoise water, a walk through a forest of giant, tree-sized Opuntia cactus leads to iguanas basking beneath them. The Galapagos dove is a reliable sight along the trail, and with some luck you may also spot the Galapagos snake or the Galapagos hawk.

Despite the name, Los Gemelos aren't volcanic craters. They're twin sinkholes, formed when empty underground magma chambers collapsed, set in the misty highlands of Santa Cruz and ringed by dense, endemic Scalesia forest. A trail loops around both rims through some of the lushest vegetation in the islands, one of the better places in the archipelago to spot a short-eared owl hunting in daylight, and, with patience, the increasingly rare vermilion flycatcher.

A small tuff-cone islet just off Santa Cruz's northwestern shore, Eden Islet is explored by panga and snorkel only. The clear, shallow water is a strong bet for green sea turtles, rays, and reef sharks, especially near the mangrove fringe, and blue-footed boobies are often seen diving nearby. Marine iguanas in their reddish breeding colors line the black rock, and a small blowhole occasionally sends spray into the air when the swell is right.

Sierra Negra's caldera stretches 10 km north to south and 9 km east to west, one of the largest volcanic calderas on Earth. The more commonly walked route to Volcan Chico crosses relatively recent lava flows with sweeping views toward the volcanoes of Isabela and neighboring Fernandina; a longer trek reaches a system of active fumaroles known as the Sulfur Mine. This is a geology-and-scenery visit, and wildlife isn't the focus here.

At first glance Punta Moreno looks like little more than a lava flow at the base of Cerro Azul, but its black surface holds a series of lagoons with a surprising amount of life. Flamingos are a fairly good bet in the pools, and paint-billed crakes, white-cheeked pintails, and common gallinules turn up for those willing to watch the water closely.

Fernandina is the only major island in the archipelago with no introduced species, which makes Punta Espinosa one of the most pristine wildlife encounters anywhere in the Galapagos. A wet landing brings you onto black lava draped with the largest gathering of marine iguanas in the islands, alongside Galapagos penguins and flightless cormorants, both drawn here by the cold, nutrient-rich current. Around June, when marine iguana hatchlings emerge, keep an eye out for the Galapagos racer snake hunting along the nesting zone. Snorkeling here is a rare chance to watch marine iguanas feeding underwater, a behavior found almost nowhere else.

Puerto Egas stands out for its black volcanic sand and a shoreline where land and sea meet in close quarters. Galapagos hawks are often seen along the walk, and at the far end waits a colony of Galapagos fur seals tucked into shaded rock grottoes, one of the more reliable places in the islands to see this endangered species.

A relaxed, sandy stop on Santa Cruz's north shore. A lagoon just behind the beach occasionally draws flamingos and other shorebirds, and the beach itself is one of the archipelago's main sea turtle nesting grounds, most active between December and June. It's an easy visit, as much about the swim as the wildlife.