It's Saturday morning and the sun shines brightly on Tung Lung Chau, a beautiful island to the south of the Clear Water Bay peninsula. Birds wheel overhead, waves crash onto the shore and the thrum of distant boat engines can be heard from the channel.

Accessible only by kaito ferry services at the week-ends and on public holidays, the island's permanent residents are a couple of families running noodle shacks. Tung Lung Chau is also home to a 300-year-old fort, the largest ancient rock carving in Hong Kong and one of the loveliest campsites in the territory. And it is a haven for rock climbers.

Tung Lung Chau boasts two fantastic cliffs, Technical Wall and Sea Gully, which are reached by scrambling over rocks on the northeast of the island. The sight is extraordinary - 30 or so climbers, roped to the wall or belaying (exerting friction on a rope) from below, enjoying the sun, sky, sea spray and jagged grey rock.

There are very few other cities in the Asia region where, within literally 10 to 20 minutes of stepping out of your home or work, you can be at the foot of a crag

Hong Kong is a remarkably good place in which to climb. At any given moment during the day, it is likely someone, somewhere in this city of seven million people is clinging tightly to a rock face, arms pumped and heart pounding. Some of the best known climbing areas are found, predictably, in the country-park lands of Lantau, Kowloon Peak, Lion Rock, Beacon Hill, Cape Collinson and Shek O. But what makes Hong Kong so interesting is that some of the rock faces are very close to the city centre. If you look carefully beyond the skyscrapers, you may well see a climber on the slabs.

"There are very few other cities in the Asia region where, within literally 10 to 20 minutes of stepping out of your home or work, you can be at the foot of a crag," says Francis Haden, one of Hong Kong's best-known climbers. "And the quality of climbing is very good here."

Haden is a mining engineer for Leighton Asia in Hong Kong, in charge of blasting on many tunnel and site formation projects in the city. As he speaks, he hangs cheerfully in his harness 10 metres up on Technical Wall. Five metres to his left, a lean and muscled climber reaches for a tricky move.

Haden discovered the sport as a teenager, in Britain. Since moving to Hong Kong for work in 2010, he has created more than 140 climbing routes in the city and many more in China, Thailand and Vietnam.

Rock climbing is divided into four categories: traditional, or "trad", climbing; sport climbing; bouldering; and free solo climbing.

Trad and sport climbers use a rope. However, with trad climbing, the participant must place his - or her - own protection (nuts, cams, bolts, hexes or pitons) in the rock, to safeguard their ascent. The climber starts at the bottom of a route with a rope attached to their safety harness. The type of protection taken from a climber's harness and thrust into the rock will depend on the size, shape and position of the crack or outcrop they want to use as an anchor. The climber slots the gear in place, checks it's safe, hangs a piece of equipment called a quickdraw from the gear and then clips in the rope. If the climber slips, the rope pulls on the protection and arrests the fall.

In Hong Kong, there are some fabulous places to rock climb

With sport climbing, the protection, in the form of bolts, is already fixed onto the rock face. The climber clips the quickdraws into the bolts and attaches the rope. Nearly all of Hong Kong's routes are bolted.

For both the trad and sport versions of the activity, the climber needs a buddy on the ground to belay, by holding the rope tight with a device.

Bouldering is climbing without a rope or harness and is usually done to a height of about six metres. A mat is placed underneath the climber to cushion a fall. It is a concentrated way of practising, performing moves and building strength.

Free solo climbers ascend without any bolts, ropes or equipment. That type of climbing is inherently dangerous.

Hong Kong is blessed with complex and interesting geology. All of the three major rock types - igneous, sedimentary and metamorphic - are found in the city, with more than 400 million years of activity visible in the landscape.

"In Hong Kong, there are some fabulous places to rock climb," says Chan Lung-sang, a professor of earth sciences at the University of Hong Kong, who has published a coffee-table book called Geological Heritage of Hong Kong. "The best rock-climbing sites are on granite or volcanics."

About 40 per cent of Hong Kong's bedrock is granite and another 40 per cent is volcanic. Sedimentary rocks account for 10 per cent.

"The sedimentary rocks form the more low-lying hills as they are easily weathered, so they don't form big cliffs. Sedimentary rock is no good for climbing but granite and volcanic rock is perfect.

Women are often better than men. This is because men focus on their strength whereas women have better flexibility and know how

"Granite is a kind of rock formed by the crystallisation of magma at great depth inside the Earth's crust," says Chan. "Some of those molten rock materials manage to get onto the surface in the form of lava or in volcanoes but the majority of the rock material stays inside the crust, where it gradually cools and solidifies into one of the strongest rocks in the world. El Capitan, in Yosemite [National Park, in the United States], well known for rock climbing, is a huge piece of granite.

"To make good climbable rock, you also want joints in the rock. This provides places to grip and footholds. Joints are made through a series of compressions and cracks. So, you start with a huge piece of granite mass. Later, because of tectonic motion and crust movement, it cracks. Typically, a lot of these rocks have joints.

"Shek O is a good piece of granite that has cracked. You don't want too many joints as it will break apart, just enough to make it favourable for climbers."

In the Jurassic period, more than 140 million years ago, two plates collided beneath what we now call Hong Kong, resulting in spectacularly huge volcanic eruptions. Each eruption produced a huge ash column, some of which were several kilometres thick. When the columns collapsed, thick layers of ash were deposited around the volcano. This ash became the volcanic rock that is now prevalent in many areas of Hong Kong. The eastern side of Hong Kong, the Sai Kung peninsula, is made of volcanic rock at least 400 metres thick. The centre of Hong Kong Island is volcanic, as is the bottom half of Lantau.

"Tung Lung Chau is volcanic - a rock type called tuff," says Chan. "This rock is good for climbing because it is very strong and extremely fine grained. Crystalline rock, both granite and volcanic, has one nature - all the minerals interlock with each other, which makes the rock intrinsically strong. This is unlike sedimentary rock, where the minerals are fragmentary."

Haden is drilling into the tuff on Technical Wall in order to place some new bolts.

"There have been a number of climbing accidents in Hong Kong as a result of old bolts that need replacing," he says, proving his point by extracting a rusting fixture.

There have been a number of climbing accidents in Hong Kong as a result of old bolts that need replacing

Haden introduced chemical-fixed bolts to Hong Kong. These will last for up to 50 years and are considered the best fixing available. Each bolt costs around HK$100 to install, so the average route costs in the region of HK$1,000 to bolt. Haden spends every free weekend out on the rock, bolting routes or checking existing routes are safe. In the past three years, he has also opened two spectacular new climbing areas on Hong Kong Island - Cape Collinson and Black Crag, off Black's Link Road - and is working on a new outdoor climbing area, though he won't reveal the location until it's ready.

"My professional life is focused on managing risk," he says. "What I do for a living involves the specialised use of explosives. Recreationally, risk has become a core aspect of the activities I enjoy, be that caving or rock climbing. However, there's calculated risk and there's unnecessary risk and I'd rather be on the right side of that equation. That's what motivates me."

Rock climbing has come a long way since it arrived in Hong Kong in the 1950s. According to the book Rock Climbs in Hong Kong, by Brian Heard, the earliest accounts of climbing come from the post-war period, when a group of soldiers attempted to summit Lion Rock. The attempt was not a success and, according to climbing lore, one person died. In 1956, a British Royal Air Force mountain rescue team climbed many peaks and started to set the scene for later climbers, two of whom wrote guidebooks in 1959 (a mere 100 copies of a book by Captain J.F. Bunnell were printed) and 1968 ( A Guide to Rock Climbing in Hong Kong, by D.C. Reeve), which is out of print.

The most recent guidebook, Rock Climbs in Hong Kong, was published in 1994 and "took a pretty old-fashioned view of what should be included, i.e. [it] mostly focused on routes using trad protection rather than sport climbs in which bolts have been placed in the rock", says Stuart Millis, an engineering geologist at consulting firm Arup and an avid climber. "As most of the good climbing in Hong Kong is bolt-protected this meant it wasn't that relevant and most people were relying on bad photocopies or faxed pages of [personally produced] guides for the different climbing areas.

"I started the website [Hong Kong Climbing] as a way of collating and improving on these and giving the climbing community and visiting climbers somewhere they could find information on the areas available and record any additions. The website's grown and we now also have articles that give advice on starting out, as well as forums where people can ask questions, look for climbing partners, that kind of thing.

"The rise in climbing gyms has changed the sport a lot over the past 15 to 20 years, both in terms of making the sport more accessible to people who otherwise wouldn't get much opportunity to try it, as well as allowing people to train and get really strong in quite short periods of time," says Millis, who arrived in Hong Kong in 1999. "This and the development of sport climbing, which allows you to try really hard climbs in relative safety, and bouldering have made the sport much more gymnastic in nature and increased its appeal, especially with the younger generation."

Hong Kong is home to several indoor climbing or bouldering gyms - three of them government owned. The government also operates four outdoor sport-climbing facilities, at Shek Kip Mei; Shun Lee Tsuen, Kwun Tong; Po Wing Road, Sheung Shui; and Tin Fai Road, Yuen Long. The YMCA owns a spectacular 18-metre-high outdoor climbing wall in King's Park, Jordan, and has an indoor wall at its premises in Tsim Sha Tsui.

"This was the first artificial climbing wall to be built in Hong Kong," says climbing coach Harry Chung Ka-wai, gazing up at the YMCA's indoor wall. "It was built around 1995. People climb indoors when it's bad weather outside - raining, too cold or too hot. You can build the wall in a convenient place for easy access. People like to go to the gym but it gets boring so they look for other interesting sports."

Chung, owner of Hong Kong Adventure Consultants, which runs team-building programmes and does both route setting and maintenance at the walls, says climbing is a "whole body sport, so it's very good for you. People falsely believe that it's just about power, but … women are often better than men. This is because men focus on their strength whereas women have better flexibility and know how to move.

"Anybody can try it. Disabled people can climb. Nowadays it's great to see lots of kids climbing," says Chung, who started participating in his teens and is now approaching his 50s. "When I grew up my parents weren't so keen on climbing because it was dangerous. Now, there is so much sports climbing and wall climbing, it's much more safe."

Although Chung teaches indoors, he says, "the best places to climb are in nature. You feel the sun on your back. You get out of the office. I like to go to Black Crag and Lion Rock, partly because it's so iconic. Plus the rock face is excellent".

Wall climbers, whether indoors or outdoors, need a second person to belay. However, some people prefer to climb alone, which means bouldering.

Perry Tong Kim-ming is the operator of BoulderLand, a bouldering gym hidden on the 11th floor of an industrial building in Kwai Chung. Tong started climbing in 1997 but has focused on bouldering since 2008.

"BoulderLand was started as a private training facility among a small group of friends," says Tong. "It began as a small room with two steep walls and some training equipment - pull-up bars, finger boards, campus boards. Now, the gym is bigger but the principles remain the same.

"Bouldering is done without a rope so climbers can focus solely on the climbing movement instead of sparing part of their attention for safety precautions and the rope system," says Tong. "By its nature, bouldering usually consists of more extreme movements, in terms of power, strength, dynamics, body position and sequencing. These movements are often considered the crux, or most difficult section, of a climbing route. So, for most climbers, climbing is difficult and bouldering is crushing."

An hour of bouldering can be the equivalent of three to four hours of wall climbing in terms of exertion.

"The sport has many other benefits," says Tong. "Problem solving, focusing, learning to manage fear and risk.

"In sport climbing, the climber has to follow the desire and design of the original route setter. In bouldering, she does not rely so much on a guidebook and is totally creative.

"In our local climbing community, climbers often do bouldering on weekday evenings and rope climb at the weekend and on holidays, with very few focusing on one discipline only. Pure indoor or outdoor climbers are not very common, though you do get the odd 'gym rat'."

For outdoor bouldering, Tong recommends Tsuen Wan.

"There are five areas with dozens of boulders and hundreds of problems. The boulders are mostly standalone, generally three to five metres tall with different angles, ranging from slab, face, slight overhang, seriously steep and roof. The boulders contain a good mix of technical, dynamic and powerful problems. Climbers at all grades can find something challenging," he says, adding that climbs can be found by walking for 30 to 60 minutes from the end of On Yat Street. "And there are spectacular views of Tai Mo Shan, the city and the harbour. Lantau Island is visible at the high points."

Lion Rock remains the king of climbs in Hong Kong: it has multi-pitch routes, it's technical, it has amazing views and it's exposed, which makes it nail-biting.

"It's a really great place to go and get scared," says Haden.

The "Lion Rock spirit" was central to the 70s RTHK television drama Below the Lion Rock. The theme song is considered to be the embodiment of the Hong Kong people's fight for a better life. So it seems no small coincidence that a group of climbers, known as Hong Kong Spidie, after the comic-book hero Spider-Man, unfurled a huge pro-democracy banner from the rock last October, bearing the words "I want real universal suffrage".

The climbers interviewed for this article are careful to say they don't know anyone who was involved in this stunt and are keen to steer clear of politics. One points out, somewhat handily, that other sports use abseil techniques, too, so the perpetrators may not have even been climbers.

Back on the cliffs of Tung Lung Chau, climbers enjoy the crag, in nature, for free.

"I really love it when I see people out rock climbing," says Chan. "There are so many stories hidden behind the surface beauty of the rock. When you stop to think about what you're seeing and that it formed more than 100 million years ago, it's crazy and inspiring. I hope our geological heritage can be preserved forever, so that future generations can see the sites as we do today. Sadly, this is unlikely given Hong Kong's unrelenting pursuit for economic and tourism growth.

"People must get out there, look at the rock, climb on the rock and appreciate it before it's gone."

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