Most travellers fly into Dili without realising they are landing beside one of the most extraordinary stretches of ocean on the planet. Just offshore, a narrow channel plunges to depths of over 3,000 metres. This is the Ombai/Wetar Strait — and it is a superhighway for whales and dolphins on a scale that few places on Earth can match.
The Corridor That Connects Two Oceans
The Ombai/Wetar Strait is fed by the Indonesian throughflow, a massive ocean current system that connects the Pacific to the Indian Ocean. Approximately 30% of all water moving between those two oceans passes through this corridor — around 5 million cubic metres per second, squeezed through a gap just 25km wide between Dili and the island of Atauro. The result is a bottleneck of extraordinary biological richness. Everything the current carries — fish, turtles, sharks, plankton — is funnelled through, and where food concentrates, cetaceans follow.
Marine biologist and whale ecologist Karen Edyvane, who has spent years surveying Timorese waters, puts it simply: “We think it’s globally significant. In 2007, we did detailed aerial surveys and spotted 2,000 animals in a single day.” Her team has recorded at least 24, possibly 25 species of cetaceans in Timor-Leste’s waters — a figure that places the Ombai Strait among the top cetacean hotspots in the world.
Dolphins, Superpods, and Risso’s
Common dolphin sightings are almost guaranteed on any boat trip out of Dili. But the Strait is also known for superpods — aggregations of hundreds of individuals, sometimes multiple species together, feasting on baitballs as seabirds and tuna swirl at the surface.
Among the rarer species, Risso’s dolphins stand out. Recognisable by their distinctive white heads — scarring accumulated from years of male-on-male sparring — they are elusive and rarely photographed underwater. Encounters are not guaranteed, but when they happen, they are unforgettable.
Scientists believe superpod formations serve multiple purposes: coordinated hunting, protection from predators, or simply the social bonds that make cetaceans such compelling animals to observe.
Sperm Whales on the Doorstep
The Ombai Strait is also home to sperm whales, drawn by the deep water and the abundant squid that live in it. Using a directional hydrophone, researchers have detected their characteristic clicks — a rapid acoustic pulse they use to echolocate and track individual squid at depth. A regular dive can last 40 to 50 minutes, the whale descending to extraordinary depths before returning to the surface.
Encounters with sperm whales in the water are possible, though never easy. These are large, intelligent animals with well-developed social structures, and they do not ignore the presence of divers. Getting close requires patience, skill, and a good measure of luck.
Plan Your Trip
Whale-watching boat trips operate out of Dili, typically running half-day or full-day excursions into the strait. The best season is May to November, during the dry months when seas are calmer and visibility is at its best. Combined with the diving available on the reefs along Timor-Leste’s north coast, a trip to Dili can easily fill a week with remarkable wildlife experiences — most of them within minutes of the shore.
Watch the Full Series
The Ombai/Wetar Strait and its cetacean life was documented in Timor-Leste from Below, a wildlife series produced by Scubazoo.