Brunei is divided into four districts (), namely Brunei-Muara, Belait, Tutong and Temburong. Brunei-Muara District is the smallest yet the most populous, and home to the country's capital Bandar Seri Begawan. Belait is the birthplace and centre for the country's oil and gas industry. Temburong is an exclave and separated from the rest of the country by the Brunei Bay and Malaysian state of Sarawak. Tutong is home to Tasek Merimbun, the country's largest natural lake.