There are a few caves, mines, and tunnels in Hong Kong that you can explore. Here the very basics that you need to consider.

Gear. Good grip shoes on rocks and mud. In most routes, intermediate trail running shoes suffice. Most surely you will make them completely wet. Full article explaining further about shoes.

Small backpack. You don’t want a bulky bag on you that will make your way in narrow passageways more difficult. Depending on the route you can leave them at the entry.

A good torch or, even better, a headlamp, so that you have both of your hands free. Bring some spare, just in case. Well charged mobile can be used for an emergency only. More information below.

I would highly recommend using a helmet. The main purpose is to avoid hitting inadvertently “stalactites” or other hanging objects with your forehead. Also in case of rocks falling from above, mainly from fellow hikers in your group… If you dislodge anything while scrambling, shout “rock” and if you are under, do not look up… I learned the hard way how painful/dangerous a falling rock can be. Do not be as stupid as me. A cap, beanie, or hoddie can be useful if with no helmet, so that at least you minimize the earth and others that could end up on your head/hair.

Gloves might be handy too, to avoid getting scratches with rusty metal pieces. Any type would do. From most to less protective that we use.

Clothes that you do not mind getting dirty and wet. I like them to cover my legs and arms fully so that I have some protection if going through really tight areas or I want to try to climb/descend through siphon like structures. Some use knee and elbow pads for extra protection.

The temperature in caves tends to stay the same year-round, usually close to the average annual temperature for the region where it’s located. In Hong Kong this is approximately 23°C at the sea level. A bit lower in higher altitudes, but around 20°C for most caves visited. This means that you will feel significantly cooler in summertime and warmer in winter.

The latter causes that wildlife, mainly reptiles, can get into the entrances to enjoy the warmth. So beware of snakes. Just let them a clear escape route. Full article about it.

How to navigate the different paths. Most of the tunnels in Hong Kong are simple, with a main corridor with small branches that have dead ends shortly after. We therefore usually just use the simple technique of going always to the first option on our right, so that we explore all the possible corners. If complex structure, you could use chalk to mark your way. Another option is to take a strong long string or thin rope. Tie one end on the entrance and take the rope with you. We have never use it.

We tend to find water in quite some of the galleries. It is one of the reasons why we tend to cave in wintertime. Drier months + with no problem with the temperature, as previously mentioned.

Avoid going on your own, nor with a too big a group. Let someone out of the group know where you are heading and your expected schedule. Let them know that everything was fine once out. Do not trust ropes or others set by previous groups and all the usual security recommendations in a stream hike.

Be respectful of the cave dwellers. You will find bats in most. Keep relatively quiet. Do not shout, nor produce high pitch sounds that highly disturb them. If you are quiet enough they might continue sleeping while you pass. If you wake them up and they start flying, get really close to the walls so that you let them a clear exit and leave the spot immediately so that they can settle down. UPDATE: In 2021 we found tunnels with way more bats. I guess, because of the colder winter, also because we went to less-visited tunnels. So I checked further how to behave with them. It seems that red light disturbs them significantly less and therefore I carry a red filter with me to put above the torch if needed. In winter, waking them up can hurt them badly, even kill them, due to different reasons. They can deplete their energy stores flying when there are no insects available to eat. That’s why they are in semi-hibernation mode. Big colonies might have babies within and the mums could drop them if suddenly awaken and feel the urge to fly. For pictures try to use as little light as possible, minimize the number of flashes or direct light from your torch. Do not get too close and if you do, separate as soon as possible so that your heat does not disturb them. A bandana or face mask can be a good idea to avoid to minimize possibilities of getting contact with urine or fungus that tend to be around bat colonies and can be harmful to humans.

Here an article from SCMP with more information and the map with most of the mines.

In the caving category you can find those of which I have written about.

If you enjoy the activity consider visiting real big caves abroad. One of the most memorable things done in my life.

More rules from the pros.

Headlamps: The unit to measure the quantity of light emitted per unit of time is called lumen. Everything else being equal the higher the number the brighter the light. Here the ones we have been using for a while as examples.

I have been using the Petzl Tikka r+ for almost a decade for trail running and emergency uses. Slightly less than 200 lumen max output is not bright enough to feel comfortable in pitch dark tunnels for most of my friends. Definitely not good for photo taking. That is why I usually bring my 900 lumen diving torch to illuminate the pics further. It has an attachable red filter too, which, as previously mentioned, is really handy when we find bat colonies. It is a scuba torch and therefore extremely waterproof. It is also supposed to be water-cooled and therefore I can not keep it switched on long outside without decreasing its lifespan. Finally, Summer usually brings her OnNight 710 from Decathlon with max 300 lumen. This is a good starting level even for photo taking undergrown.

Now that I am thinking to buy a new one, what are the things that I am considering? Foremost light output. Not only the maximum lumen and how many intermediate spots there are. Also if it has a red light, that allows you to maintain your night vision and is less intrusive for wildlife. Researching I discovered that some torches have also special green beams (that help with detail at night, like on a rocky trail, or reading contour lines on a map) and blue beams (for hunting). The optic and the beam pattern is also important. Even with the same lumen figure, two torches can feel completely different. The terms used are Spotlight for a more focused beam Vs Floodlight for a wider defused beam. The former will allow you to see further ahead and the latter will illuminate a bigger area around you but not so far (I prefer it for pics). There are headlamps that have separated lamps for each function that you can use also together for maximum output. A video explaining all this and way more.

Waterproofing. Considering how many of our activities include being close or in the water it is almost a must. I am seeing more and more models these days with IPx8 certification.

Weight and comfort. If you are going to be wearing it for long this is something important to consider. For those trail running regularly after sunset, I would go with lighter and more compact models. I do it sometimes, but not so much. Therefore I can buy a bit heavier model. The headband needs to be comfortable anyhow.

Battery life will depend on the output, battery size, and efficiency of the headlamp. Trying to figure out with the tables on the box how much each mode will last can be tricky sometimes: is it on continued mode, or does the output drop steadily in higher power modes? Checking charts, reading reviews, and watching videos to try to know more.

Rechargeable batteries are a must for me. Single-use batteries are such a waste and polluting. Nevertheless, all the rechargeable batteries are not made equal. Proprietary formats that can be used with one specific model are not so good. Now I prefer torches using 18650 type batteries (same as my diving one, so that I can swap) ideally of max capacity (3500mAh), and if chargeable directly with a C type USB then is a winner! 🙂

So with all the previous, this could be my headlamp/torch for the next decade.

Maintenance. For those of you using them sporadically, the usual recommendation is to clean them before storage and remove the batteries half to full charged. Store all in a dry, well-ventilated area, out of direct sunlight. Read the manufacturer’s manual for specific requirements/recommendations.