Soufrière is St. Vincent's tallest volcano, and it occupies one-third of the island's northern end. The night before I attacked it, I had some callaloo soup. It will restore your blood if you fall sick, the natives told me. I thought, as I was drinking the thick green slurry, that if I drank it every day it could add a decade to my life expectancy.

Early the next morning, I drove to the base of the volcano. The trail was littered with soda cans and candy and snack-food wrappers, the inevitable detritus of a popular place. But on the side of the road there were small yellow blossoms, called Soufrière flowers. We walked up through dramatic changes in vegetation, from cultivated flatlands, through montane rain forest, then the palm break between 1,700 and 2,100 feet above sea level, and finally elfin woodland right below the top. The air became colder; this didn't feel like the Caribbean anymore. It was a pleasant relief, though, and made the tough climb easier to bear.

I had the top to myself. I peered over the edge of the crater: It was a straight drop of about a thousand feet to the bottom of the mile-wide bowl. In the center, over the mouth of the volcano, rose a giant scab, a huge black tumor ringed by a river. I could see embers glowing angrily at the bottom. This is where the Caribbean and North American plates meet, and from my vantage point I could indeed see both the sea on one side and the ocean on the other. I felt as if the volcano might erupt at any moment. A 1902 explosion had killed 1,565 people; the most recent one was in 1979, and the villages were evacuated in time, so nobody died. I could see a satellite dish on the far side of the crater, linked to seismic monitoring sensors in the riverbed below, an early warning system for the next eruption.

Though calm, it was a scene of great moment, great activity. Fingers of cloud moved rapidly over the caldera, veiling and uncovering both the Atlantic and the Caribbean and the verdant slopes all around. The wind was roaring over the higher slopes, shaking the hard, stubbly green-yellow grasses. There were no birds, no animals. The soil was black and pebbly—ash from previous eruptions. I sat down and unwrapped my lunch, a sandwich the hotel had packed, and ate it at the top of the world. I could see everything except New York from here.

Dominica is the greenest island in the eastern Caribbean and, along with St. Vincent, one of the poorest. The island goes its own way in every way, including politically. Its government maintains cordial relations with Cuba, much to the U.S. government's displeasure. Beautiful as the island is, it is losing population, because farming isn't viable on its hilly slopes and tourism isn't on a scale lavish enough to employ large numbers of people. The capital, Roseau, becomes a ghost town after sunset, when the cruise ships depart.

One morning, I drove through fields of papaya, coffee, grapefruit, cocoa, and dasheen on the road to the forest of Morne Diablotin National Park. The forest is home to the rare sisserou parrot (Amazonia imperialis), which nests high on the slopes of 4,749-foot Morne Diablotin. I was hoping to spot one. I started seeing plenty of birds in the forest: scaly-naped pigeons, broad-winged hawks, and a rare blue-headed hummingbird fluttering about an orange tree, close enough for me to try to catch it with my outstretched hand. Flycatchers and pearly-eyed thrashers also colored the space around me.