The Ombai-Wetar Strait: Timor-Leste's Whale Superhighway

Just off Dili, the Ombai-Wetar Strait plunges to about 3,000 m and forms a migration corridor for whales and dolphins between the Pacific and Indian Oceans. At least 21 cetacean species have been recorded in Timor-Leste’s waters, and the best time to see migrating whales is October to December.

This post accompanies episode 5 of Scubazoo’s 2018 series Timor-Leste from Below.

Watch: episode 5

Watch on YouTube

A corridor between two oceans

The strait runs between mainland Timor and the islands of Atauro and Wetar. It is one of the passages of the Indonesian Throughflow, the current system that carries Pacific water into the Indian Ocean. The deep trough, strong currents and seasonal upwelling concentrate food close to shore, and whales and dolphins follow. Mission Blue describes it as a migration corridor for large whales, sharks and sea turtles, and the area is recognised as an Important Marine Mammal Area.

What the surveys found

Marine ecologist Karen Edyvane has studied whales and dolphins in Timor-Leste since 2006. A 2008 boat survey counted more than 1,000 animals in a single day along a 50 km stretch of coast. Her later surveys (2016–2023) recorded at least 21 cetacean species living in or passing through Timor-Leste’s waters and confirmed a yearly migration of pygmy blue whales through the strait. Her programme has logged more than 2,700 blue whale sightings since 2014.

Dolphins and superpods

Dolphins can be seen year-round, and the episode shows “superpods”: large groups, sometimes of more than one species, feeding together where fish are concentrated. Risso’s dolphins, recognisable by their blunt heads and heavily scarred grey-white bodies, are rarer and harder to approach.

Sperm whales

Sperm whales hunt squid in the deep water of the strait. Their dives typically last around 45 minutes, and they find prey by echolocation clicks that can be picked up with a hydrophone. More in our post on sperm whales off Dili.

Plan your trip

When: October to December for migrating whales; dolphins all year. Seas are generally calmer in the dry season.
From where: half-day and full-day boat trips leave from Dili, and some operators on Atauro also offer whale watching.
Expect: sightings are never guaranteed. Pick operators that approach slowly and keep their distance.

See our dolphins and whales guide, dive sites and Atauro Island guide.