Bitung, Indonesia

On the northeastern tip of Sulawesi, where the Celebes Sea meets the Molucca Sea in a confluence of deep-water currents, lies Bitung — a port that has served as a spice trade waypoint since long before the Dutch East India Company planted its flag. The city's natural harbor, sheltered by the volcanic bulk of Mount Klabat, has welcomed traders from China, Arabia, and the Malay Peninsula for centuries. Today, Bitung is the gateway to what many marine biologists consider the most biodiverse waters on the planet: the coral triangle's northern apex, where more species of fish and coral exist per square meter than anywhere else on Earth.

Bitung itself is an unpretentious harbor town — container ships and traditional wooden pinisi schooners share the waterfront — but its charm lies in what surrounds it. The provincial capital of Manado, thirty minutes to the west, is a vibrant, predominantly Christian city (unusual in Muslim-majority Indonesia) with a striking skyline of churches and a waterfront boulevard lined with restaurants serving fiery Minahasan cuisine. The Minahasan people have a culinary fearlessness that startles even seasoned travelers: expect dishes featuring forest rat, fruit bat, and the notorious rica-rica chili paste that sets the standard for heat across the Indonesian archipelago. For the less adventurous, the tuna — pulled fresh from the Celebes Sea each morning — is magnificent.

The underwater world is Bitung's true masterpiece. The Lembeh Strait, a narrow channel separating the mainland from Lembeh Island, is the world capital of "muck diving" — a specialized form of scuba that trades coral gardens for volcanic sand slopes teeming with bizarre, cryptic creatures. Here, divers photograph hairy frogfish, blue-ringed octopuses, flamboyant cuttlefish, and the astonishing mimic octopus, which can impersonate lionfish, flatfish, and sea snakes at will. Across the peninsula, Bunaken National Marine Park offers a contrasting spectacle: sheer coral walls plunging into the abyss, patrolled by sea turtles, Napoleon wrasse, and schools of barracuda so dense they block the tropical sunlight.

Ashore, the Tangkoko Nature Reserve provides one of Southeast Asia's most rewarding wildlife encounters. This pocket of primary rainforest is home to the Sulawesi crested black macaque — an endangered primate with an expressive face and a mischievous temperament — as well as tarsiers, the world's smallest primates, whose enormous eyes peer from tree hollows at dusk. Bear cuscus, maleo birds, and hornbills round out a cast of endemic species found nowhere else on Earth. The reserve's trails wind through dense forest to black-sand beaches where macaques forage at the tide line, utterly indifferent to human observers.

Cunard calls at Bitung on its world cruise and Asia-Pacific itineraries, with ships docking at the commercial port. Nearby ports of call across the Indonesian archipelago — from Komodo to the Banda Islands — extend the expedition into the heart of the coral triangle. The best diving conditions occur from March through October, when calm seas and minimal current make Lembeh Strait's treasures most accessible, though the strait's sheltered position allows year-round diving.