THIS TRIP IS FULLY BOOKED

The Upper Gulf of Thailand is known for its population of Bryde’s whales, also known as Eden’s whales (Balaenoptera edeni). This is a remarkable species that can grow up to 11 to 12 metres in length and weigh up to 15 to 20 tonnes. The coastal ecosystem of the  Gulf of Thailand is enriched by the nutrients of four major rivers that empty into the Gulf: Mae Klong, Tha-Jeen, Chao Phraya, and Bang Pakong. The nutrients from these rivers emptying into the Gulf of Thailand, plus mangrove trees and mudflats along the shore, contribute to the biodiversity of the Gulf waters, providing an abundance of food for the whales, such as schools of fish and copious plankton. The Gulf of Thailand is home to over 80 identified individual whales, including at least 15 pairs of cows and calves. They surface to “trap-feed” in the monsoon season, when the richness of the nutrition level in the water reaches its peak. July is therefore an optimum time to observe whales in the Gulf.

The Natural History Section of The Siam Society will lead members on a one-day boat trip in the Upper Gulf of Thailand to view these whales on Saturday, 5 July 2025. The trip will be led by Mr Jim Stent, Council Member of The Siam Society, in collaboration with the ecotourism company Wild Encounter Thailand, which will provide the boat and crew.  This one-day study trip offers a unique opportunity to observe Bryde’s whales in their natural habitat. The trip will be conducted with strict considerations for wildlife and environmental conservation, with expert guidance from a Wild Encounter naturalist and whale-watching crew, offering insights into efforts to protect these remarkable mammals and their fragile ecosystem. Participation in the trip is in support of whale exploration through a citizen science approach.

Much research has been conducted in the Upper Gulf on Bryde’s whales’ trap-feeding (or tread-water feeding), where the whales, in one of their most recognisable behaviour patterns, emerge from the water and open their mouths for a prolonged period of time. You may also spot dolphins, porpoises, seabirds and other marine species that feed on fish driven to the surface by the whales’ dynamic underwater movements.