You can find all kind of shops in Hong Kong where to buy all your needs.
Sometimes finding them though is more complicated than the outdoor paths themselves. Here some of the shops that I like for different options
· All Weather
The smallest but most efficient (and usually cheapest) shop I know in Hong Kong. Mong Kok Exit 2, walk Sai Yeung Choi southwards, turn left into Soy street and left again in the corner with Ladies’ Market. Half hidden entrance here, up the stair of the dilapidated building (little adventure on its own 😛 ) and there you are.
All your trail running and short hiking necessities might be covered here: compression gear, Ultimate Direction / Salomon and other brand running backpacks, nutrition, anti-chafing, technical socks, GPS / heart rate monitors, waterproof phone covers, etc. They don’t have many shoe options though (really reduced space). Check their Facebook page for latest products. You may want to call them beforehand (2384 8890) as their opening schedules are bit erratic. Update: The shop owner told me that they open Monday to Saturday from 12 to 9, holidays excluded.
· Racing the planet
Similar products to All Weather but higher end / pricing and with more variety. You can buy or check products on their web. Additionally, here you can find quite some brands of shoes, sleeping bags, camping stuff, snow gear, dehydrated food, etc. Sheung Wan MTR station.
Overlander has several shops all around Hong Kong. Two of the biggest are in Cause Way Bay and Mong Kok. Similar product range as Racing the Planet. A bit cheaper sometimes. Good selection of camping tents and others.
Chamonix is one of the most technical shops I tend to visit, to find specific canyoning, coasteering, climbing and thermal wear, among others. Mong Kok exit 2, walk Nelson street eastwards towards Ladies’ Market and in the corner you will find the shop. The only one so far that I know that has Five Ten canyoning / approach shoes.
It is bit messy and the shop attendants are not the most friendly. Some of them know what they are selling (which unfortunately is not the norm in Mong Kok sport shops). Not in the shoe section, in the upper second floor for: canyoning, climbing, etc shoes.
· Wan Kee XL
Wan Kee mainly focused in footwear, but they also sell some other apparel. They have shops all around Hong Kong, quite some in Mongkok. This is the biggest I have seen so far and the one which has best options for the kind of activities proposed here + nice discounts. I have bought Salomon shoes almost half the original price.
Next to the Macpherson playground
Escapade has products for triathlon, (trail) running, hiking, nutrition and others. In the expensive range. Good promotions and sales frecuently. Several locations including Causeway Bay, Central, Repulse Bay & Clear Water Bay. I did not buy mine here, but they do have swim safety devices. I did buy a dry bag for coasteering and quite some running apparel, Ronhill shorts among others.
· Ah Lai (or whatever is called)
You should be able to find this kind of stores in most modest neighborhoods in Hong Kong. For cheap cotton gloves, for example, you can try any hardware store (those selling electric cables, sockets, etc), paint shops, etc.
· Tung Chung Outlets
In your way back from any outing in Lantau island you might want to take a look at the outlets in Citygate. Sometimes they do have good priced sportswear. Here I have bought the (Quiksilver) swimsuits that I have been using for stream hikings (for years), some Nike basic gear, etc.