Suddenly I gag—every drop of moisture sucked from my mortal being. This inspires the first of several choruses of good-humored laughter. At last I spit the thing out, to one more peal of hometown satisfaction.

I wave good-bye and walk away. A hundred paces later, I have to uncap my precious bottle of purified water to rinse out the taste, and I hear them laugh again, still watching the dim-dim return to his ship.

Yet when the Orion pulls away at five that evening, there is no doubt where this explorer stands on the pivotal question: Would you rather be chewing on an authentic hunk of taro root tonight and sleeping on a straw mat under a mosquito net in the name of realism, or would you like to eat your Tasmanian oysters and kingfish with parsnip root and your loin of lamb with eggplant polenta, not in the Constellation Restaurant where you dined last night but on the upper deck under the stars at the Delphinius Café with those new Aussie friends you're running with—the drinkers and dancers, the smokers and jokers?

The ship's passengers are mainly over-fifty Aussie couples—chipper, can-do, inquisitive, droll. We attend PowerPoint lectures by war historians, ornithologists, and botanists. The dress is casual, the chatter breezy to balmy. The tropic nights are atmospheric enough without a casino or a climbing wall or a midnight buffet.

The Orion is an attempt to marry the go-anywhere ethic of a Lindblad cruise with some of the luxury of a Seabourn. It's two years old, with mythology-themed artwork on its richly wood-grained walls, and mirrored ceilings that reflect the ocean's surface racing past. The cabins have marble baths and flat-screen TVs, but for these ten days all I watch is the channel that maps where the Orion is in nautical space as our digital latitude ticks down toward the equator.

Next stop is the Louisiade Archipelago—ten volcanic islands and coral reefs that see zero mass tourism. By eight in the morning we drop anchor off uninhabited Nivani Island, a mound of jungle rising like bread from the sea, with cowlicks of coconut palms shooting up and a white beach peeking out from the far side. We are spirited over in Zodiac rubber duckies, the water so clear that we seem to levitate above the ocean floor. Even ninety-four-year-old Phyllis comes ashore and sits propped against an almond tree. Most of us go snorkeling off the beach, and our prize is a Japanese fighter plane—one of the legendary Zeroes that controlled the Pacific skies early in the war—nestled among the coral in twelve feet of water. We float above it as in a dream: the propeller bent, the cockpit empty, the control stick fuzzed over with algae, the fish ghosting in and out of the fuselage. Back on the beach, we have visitors. Some men and boys have canoed over from the next island. The elderly one is their bigman, or chief, and he tells me that Nivani was left to him by an Australian man who ran a coconut plantation here until twenty years ago. "When Dusty Miller leave, he leave everything—store and houses. It was very good!" the bigman recalls. "Then cyclone knock down all the buildings." He laughs heartily. "The worstest one!"