Tasek Merimbun Heritage Park, Heritage park in Tutong District, Brunei.

Tasek Merimbun Heritage Park is a nature reserve in Tutong District, Brunei, built around a large S-shaped lake that contains two islands. The park has forest trails, camping areas, exhibition halls, and a boat service that takes visitors out to the islands.

A hunter named Imbun is said to have discovered the lake, which led to the first settlements forming in the area around it. Over time, the site was recognized for its natural value and became part of the ASEAN Heritage network.

The lake's name is linked by local tradition to Imbun, a hunter said to have settled here with his family after finding abundant game and fish. Another legend traces it to Eng Boon, a Chinese trader who came to barter goods with the Dusun. On Pulau Jelundong, ruins of a sacred ancestral site have been found.

The lake lies about 27 km from Tutong Town and 70 km from Bandar Seri Begawan. One small island is reached by a wooden walkway; the other requires a hired boat, so arrange it at the jetty first. Chalet facilities near the lake serve researchers.

The lake water has a naturally dark color caused by tannins that leach from fallen leaves on the forest floor. This gives the water conditions different from most lakes, which allows certain rare plants and animals to live there that would not survive elsewhere.