Marsiling Tunnels

A set of tunnels puzzling Singapore, sparking numerous conspiracy theories about its origins since the late 20th century, has its mystery finally cracked. Located on Admiralty Road West and Marsiling Crescent, the World War II-era tunnels have remained hidden from sight since the British left Singapore. 

Since the tunnels' discovery in the 2000s, multiple theories have been proposed about their origins. Some thought the tunnels led to Johor, or housed an underground facility for a nearby mental hospital. The most compelling theory was that the tunnel had been an underground oil storage facility built by the Asiatic Petroleum Company (APC) for a British Royal Navy base. A 1945 map showed the location of Woodlands North Depot, once operated by APC, on the exact location of the tunnels. 

At an impressive 54 square kilometers, Her Majesty’s Naval Base occupied almost 10 percent of Singapore’s land size in the 1940s and was formerly the largest British military base in Asia. The former base is now home to Sembawang Park and Woodlands Waterfront Park. 

While the evidence was compelling, the theory was slightly off. By obtaining information from disclosed documents, British Wartime Intelligence Reports, and the U.K.’s National Archives, Singapore’s National Heritage Board solved the mystery of the Marsiling Tunnels' true origin and purpose. They have been verified as a pre-WWII fuel reserve depot utilized by the Royal Air Force, not the British Royal Navy. 

During their occupation of Singapore, the Imperial Japanese Army utilized the tunnels as an oil storage facility. According to a 1944 British intelligence report, the tunnels were renovated to have five large tanks, increasing their capacity by over 5,250 tons. 

In 2014, on the 72nd anniversary of the Battle of Singapore, the tunnels opened to the public for the first time. The National Heritage Board offered guided tours to show how the British surrendered Singapore to the Japanese. These tours also included important historical locations like Opium Hill and Tiong Bahru Air Raid Shelter. Today, most entrances have been sealed and are closed to the public, but a small entrance found by local explorers remains open.