HK Magazine Archive

Underground Hong Kong

If you dig beneath the surface there’s a whole other world out there.

PUBLISHED : Thursday, 10 August, 2006, 4:00pm
UPDATED : Wednesday, 19 October, 2016, 2:10pm

You think you know everything there is to know about Hong Kong and then one night, you drunkenly stumble into a broken storm drain and realize that actually, there’s a whole other world out there. It’s just underground. As we scurry about our busy little surface lives, little do we stop to think that under our feet lies a network of tunnels, caves, pipes and tanks that have all played a part in the story of our city.

Indeed, as Hong Kong is so constricted when it comes to space, more than any other city in the world, we have found innovative and often downright bizarre ways to put the ground beneath our feet to good use. So in a bid to work out just what’s going on down there, we take a tour of Hong Kong’s major underground attractions…

Tunnels of Gin Drinkers Line

Access: Minibus 82 from Exit B of Tsuen Wan MTR Station to the Maclehose Trail; take the trail to rest station number 7; then climb up the steps until the tunnels come into view.
Many people complain that the history of Hong Kong has been wiped away to pave the way for modernization, but if you know where to look, there is still a very distinct souvenir of Hong Kong’s past in the hills behind Shing Mun Resevoir. An entire network of World War II tunnels still exists preserved and untouched, ready for exploration. They are part of Gin Drinkers Line, and were one of the last lines of British defense when the Japanese invaded Hong Kong in 1941. However, contrary to popular belief, they were not originally built for this purpose. As local historian and author of “Ruins of War: A guide to Hong Kong’s Battlefields and Wartime Sites,” Jason Wordie, explains, “The tunnels were originally built in 1938 as a new line of defense to protect the reservoir. When the Shing Mun reservoir scheme was initiated in the early 1930s, it was the largest water project in the British Empire so if it had been captured it would have been like turning the tap off.” The tunnels were named by First Battalion, Middlesex regiment. As they were Londoners, they developed their own system of navigating the tunnels by labeling them with the names of London streets, such as Shaftsbury Avenue and Oxford Street. This ingenious method meant the British troops could easily run through the complex network of tunnels in the heat of battle.

Unfortunately, their tactical maneuvers did not save the Royal Scots and Indian Units who were stationed in the tunnels when the Japanese invaded in 1941. The troops held the tunnels for just three days before being overwhelmed. Today, the tunnels remain open and well preserved and it is even possible to climb in. You can still see the names of the tunnels clearly marked on the walls.

Ma On Shan Iron Ore Mine

Access: Off the Ma On Shan Country Trail, Sai Kung Peninsula, New Territories
Hidden in the undergrowth off the Ma On Shan country trail lies the entrance to an abandoned mine. While Hong Kong might not be considered a mining hub, between 1953 and 1976, the Ma On Shan Mountain in the New Territories was home to a busy iron ore mine. As the demand for steel declined in the 70s, the mine’s fate was sealed along with its entrance, leaving a network of empty tunnels beneath the mountain. At its busiest, the mine employed over 400 workers and produced over 400,000 tons of steel a year, hauling the ore from the ground on an electric train.

While it is possible to break into the tunnel network, it is extremely dangerous to descend unguided. Not only are the tunnels extremely difficult to navigate, but many of them are waterlogged and sections of the roof are unsafe. However, the Institute of Mining Engineers ( occasionally takes groups of people around 100 meters down the tunnels to the miner's canteen.

Stanley Sewage Works

Access: 37 Wong Ma Kok Road, Stanley
No one wants to look out their window and see a sewage works in full action, so it’s no surprise Stanley Sewage Works is hidden in a natural cave below the surface. As Michael Chan, engineer with the Drainage Services Department, explains, “We needed a sewage works in the area to service Stanley Peninsula, Tai Tam, Chung Hom Kok and the Red Hill areas," he says. “But the area that was most convenient to build the works was prime real estate and a sewage works isn’t exactly a very attractive construction, so we decided to build it inside three large caverns.”

Indeed, the only clue to the outside world that the sewage works even exists is an unobtrusive entrance that looks like a car park and a few overgrown ventilation shafts. As we wind our way down into the bowels of the works, it starts to feel like a proper villain’s lair. “I often think this could be a great James Bond set,” yells Chan above the din of power filters as we cover our noses and enter a palatial entrance cave, covered in a network of pipes and sewage tanks. There are three caves, each around 120 meters long, 15 meters wide and 17 meters high and all lined with filter tanks of swirling brown sludge. A faint mist hangs in the air and the distinct smell of putrid eggs swirls above the rancid brown sludge floating on the surface of the tanks.

Upon arrival, the sewage goes through a pummeling filter system, to remove all the delicately named “large sewage particles.” It then passes through a detritor to remove all the grit and then enters the de-nitrification stage, where the water is blasted with air causing the bacteria to rise to the surface and form an ominous looking yellowish brown scum, which is then skimmed from the water. During this process, the remaining dirt particles settle on the bottom of the tank and are also skimmed away, and finally the water is disinfected with chemicals before being pumped two kilometers out to sea from Tweed Bay. All those inauspicious “large particles” and sewage scum are then trucked off to a landfill site. Meanwhile, an army of scientists works like frantic ants to ensure the fumes pumping out above ground are not toxic or harmful to the environment.

Air Raid Shelters and Bunkers

Access: Corner of Queen’s Road East and Kennedy Road, Wan Chai and Crown Wine Cellars, 18 Deepwater Drive, Shouson Hill, 2580-6287
Other well-preserved relics from World War II also remain dotted all over the city: civilian air raid shelters and military tunnel networks and ammunition bunkers. Although not accessible to the public, there are currently 82 disused tunnel networks in various locations across Hong Kong, 29 of which were purposely constructed as air raid shelters. Many of these bunkers remain hidden from view, but there are still visible entrances to shelters under St. Andrews church on Nathan Road in Tsim Sha Tsui, under the old army married quarters on Supreme Court Drive and at the corner of Queen’s Road East and Kennedy Road in Wan Chai. These air raid shelters were initially built by the British in 1940 as part of the pre-war preparations and in anticipation of an air attack on Hong Kong. But between 1944 and 1945, after Hong Kong had fallen to the Japanese, the US Air Force bombed the city and the air raid shelters were used to shield thousands of civilians.

Never one to miss a great land opportunity, the government has been trying to scheme up a way to put the bunkers and air raid tunnels to good use for years. One of the bunkers on Queen’s Road East is being used as a low-level radioactive waste dump. (Even more dubiously, a dead body was found there in 2001.) Another bunker under Shouson Hill is used for storage of soil and rock samples and a third under Lei Yue Mun is part of the Hong Kong Museum of Coastal Defense. Meanwhile, Crown Wine Group (18 Deepwater Drive) has converted an ammunitions bunker under Shouson Hill into a wine cellar.

Otherwise the shelters remain untouched, despite the fact that everything from a carpark to a library has been suggested as a way of putting the spaces to use. The fact is that without proper ventilation or electricity, they are likely to remain an undisturbed reminder of war. Indeed, the most likely outcome for these bunkers is that they will ultimately be knocked down as more and more is built on top of them.

Tai Hang Tung Flood Storage Tank

Access: Beneath Tai Hang Tung Recreation Playground, Tai Hang Tung Road, Sham Shui Po.
Ever wondered where all the water flooding Mongkok during every storm ends up going? Sometimes the sheer mass of water that descends on the city is impossible to ferry out to sea quick enough. So for years, Mong Kok, Yau Ma Tei, Tai Kok Tsui, Sham Shui Po and Tai Hang Tung were regularly subjected to floods that inconvenienced everyone there, and sometimes even proved fatal. “It got so bad that in the late 90s people were referring to Nathan Road as Nathan River,” explains the Technical Secretary for the Drainage Services Department, Robin Lee. “There was often over three feet of water flowing through densely populated areas such as Mongkok.”

After a particularly bad year in 1997, the government decided they needed to expand the storm drainage system in order to cope with the sheer volume of water hitting Kowloon. “At first we were intending to extend all the storm drains, but not only would it have been a massive project, but it would have been hugely disruptive to traffic and residents in the area," explains Lee. The solution was a colossal tank beneath Tai Hang Tung playing field connected to Kai Tak with a gigantic storm water transfer tunnel. During a heavy storm, the water descending on Kowloon Tong is diverted away from the heavily populated areas to a huge storage tank. It then remains in the tank until the rainfall abates (it’s usually no longer than one hour from the start of heavy rain), before finally being pumped back out through the drainage system to the sea. This way the system is rarely overwhelmed with water. So during a summer rainstorm, for around an hour, 100,000 cubic meters of water swirl beneath the ground as kids play in the rain on the fields above. Needless to say, the tank was full when we wanted to visit, so unless we had gotten ourselves some industrial diving gear, there was no way of getting down there to witness it firsthand. However, Robin Lee says after you descend the spiral staircase down into the depths of the tank, it looks very much like an underground car park. “It is really huge, about the size of a football field and as there is no permanent lighting, it’s a very dark, dank place,” he explains.

Japanese Kamikaze Caves

Access: Along the coastal path from Yung Shue Wan to Sok Kwu Wan
The Japanese also left their mark on Hong Kong during WWII. After they seized Hong Kong, they began preparing for an anticipated attack on the Lamma Channel. In defense, they built a series of caves across Lamma, which later became known as the Kamikaze Caves. The Caves were used to hide suicide boats loaded with explosives (known as “shinyo” or “kamikaze boats”). As Jason Wordie explains, “The Japanese would have driven out toward any incoming vessels on a suicide mission of destruction. However, the boats were never used: the Japanese surrendered after the atomic bombings, and as a result, Hong Kong was recaptured without being fought over.”

The caves are now rugged reminders of the Japanese occupation and it is still possible to explore them if you follow the coastal path from Yung Shue Wan to Sok Kwu Wan. About a kilometer from Picnic Bay, there are signs to the Kamikaze Caves and a short climb along rugged coastline takes you to them. Although there is little left of any Japanese structure, with a little imagination and the sound of waves crashing in the background, you can just about picture crazed little boats powering their way out to an incoming ship.

West Refuse Transfer Station

Access: Swire SITA Waste Services, Mount Davis Rd., Kennedy Town
Much like the Stanley Sewage plant, there are some parts of Hong Kong life that we just don’t want to look at - and that includes a garbage transfer station.

A big waste depot is discreetly hidden behind an entrance on Victoria Road. Everyday, the orange refuse collection trucks arrive with their loads of rubbish. Run by Swire SITA services, the trucks are weighed as they arrive (the government is charged by the weight of the trash processed). The trucks then rumble down a winding tunnel deep into an enormous cavern, 27 meters wide and 30 meters high, where the rubbish is deposited. Giant trenches line the walls of the cave, where the garbage trucks deposit their loads. A conveyor belt transports all the rubbish to a deeper pit at the end of the cave. When this pit is full, it activates a giant piston that compacts the contents and stuffs them into containers. These containers are then taken to another cave deeper below, where new trucks await to transport them to a landfill in the New Territories.

A single garbage truck can visit the depot up to 105 times a day, bringing over 1,000 tons of waste to the cave. Although the smell of rotting refuse is overwhelming, the workers who busily sweep the spillover garbage into the trenches say you quickly become accustomed to it. Amazingly, this is the first underground garbage transfer station in the world. Despite costing $640 million to build, Swire saved themselves millions of dollars: It would have cost much more for the land on the rock above if they chose to keep the station above ground.

Weird stuff unearthed in Hong Kong

Unexploded bombs from World War II: In April this year, a stash of World War II bombs and a grenade were found buried below Cheung Sha Wan. Bomb disposal experts were called in when construction workers at a drainage site discovered 588 grenades and bombs, 188 of which contained live explosives. Sixteen of the explosives were deemed too unstable to remove from the street and residents were evacuated before the bombs were destroyed.

Fuses and explosives: In January 2000, it was reported that several fuses and explosives were unearthed at a construction site near Cityplaza in Tai Koo Shing. Workers left behind the explosives in 1982 after blasting the intersection of Kornhill Road and King’s Road in Quarry Bay.

A Ganoid Fossil: In 1959, an archeologist discovered a fish fossil on Lantau Island. It was sent to the British Museum in London for examination, where experts discovered it to be a fossil of a Ganoid (a primitive fish) that is over 150 million years old.

6000-year-old hammer: A 6000-year-old hammer was unearthed on Lamma Island along with prehistoric stone pottery and bronze pots and weapons. These artifacts were the first evidence of human activity in Hong Kong.

Dead bodies: In June 2003, a woman was found buried on the hillside in Sheung Kok Shan Tsuen, Lei Muk Shue. A 44-year old man was later charged with her murder.