The boat headed north through open sea. We slowed as we approached a sheltered lagoon, the water below us so clear that the boat seemed to levitate above the coral. Indonesian crewmen — whom I am barred from naming but who do most of the actual work — unloaded the boat, stashed our luggage in the lean-to and gave us a vague indication of where we might find coconuts and how to split one open. They also left us with a handheld metal grate: If we somehow caught a fish and built a fire, we could use the grate to cook the fish over an open flame. Cerezo handed us a walkie-talkie and showed us how to use it. My wife, who grew up in Manhattan and is spooked by silence, asked every conceivable question — about stingrays, about the tides — in the manner of a child forestalling bedtime. Then they shoved off, and we were alone.

We walked along the beach. We were ostensibly gathering wood for kindling, the idea being that the wind might die down and we would try, and almost surely fail, to build a fire. I also picked up a coconut and carried it under my arm like an ungainly talisman. This was a game, and, though we felt a bit silly about it, we were attempting to follow the rules.

Mostly, we engaged in meta-tourism, talking about what it was like to be on a desert island. We noticed things, wondered what it meant that we were noticing them, took photographs to remind ourselves what we’d noticed. We had asked Cerezo everything we could think to ask, but we had failed to ask the primary question: What is the point of this? I realized that I had unconsciously and unrealistically hoped that sheer geographic remoteness would strip me of self-consciousness. Yet here I was, still inside my own brain, still observing what I was doing as I did it.

I expressed some of these thoughts as we walked along the beach, further distancing myself from the moment by analyzing the ways in which I felt distant from the moment. Then I saw a crab. It was between two rocks, the rocks were far from each other, and so the crab was exposed, unsure whether to scurry left or scurry right or play dead. It was plump and crimson against the white sand. It raised its pincers, opening and closing them in a disturbingly Pixar-ish gesture of helplessness. I bonked it on the head with the coconut. ‘‘I’m really doing this, I guess,’’ I thought, but what I said was closer to a panicky preverbal squeal. The crab was still squirming, or parts of it were. I slammed the coconut down again, grinding the crab’s body into the sand. It stopped moving.

What were once academic questions became suddenly immediate. How much daylight did we have? How much firewood? My wife was gripped by a fierce conviction that the crab should not have died in vain. We rushed back to the lean-to and found the lighter. It didn’t work. Before we could decide what to do next, we spotted another lighter, half-buried in the sand: This one worked. We pried open the coconut and pulled out a handful of the rough fibers inside — one of the Docastaway employees had mentioned, and we now recalled, that these fibers were supposed to make good kindling. They ignited. We cleared a spot in the sand and added more of the fibers, then small sticks, then larger ones, until we had a decent fire. We propped up the metal grate in the fire, put water in the cookpot and balanced it on the grate. The sun was setting — a desert-island-cartoon spray of pinks and golds — but we only had time to glimpse it. We hardly talked, except to exchange practical information: ‘‘Stand here’’; ‘‘Hold this.’’ I scraped as much sand from the crab as I could. The water came to a boil, and I dropped the crab into the pot and covered it. Meanwhile, my wife found another coconut and bore a hole in it using a sharp-tipped piece of bamboo she’d found on the beach; then she carried the coconut to a stump, raised the machete above her head, split the coconut in two and drank the water from it. We worked for what turned out to be two hours, though neither of us was aware of how much time was passing or how we might look or why exactly we were doing what we were doing. After a while, I removed the pot cover, laid it upside-down on the stump, dumped the crab onto it, cracked open one of the claws and wrenched out a bit of steaming meat.

‘‘It smells like crab!’’ my wife said.

I took a bite. ‘‘It tastes like crab!’’ I said.

We had expended more calories than we ingested, but we felt satisfied. We never thought of opening the granola bars. Instead, we hacked open another coconut, drank its water and then let the fire die down so that we could look at the stars while we ate chunks of coconut and crab meat. It was the least-photographed span of our trip, and the one that we will remember the longest.