From the perspective of safely entering and exiting caves, cave exploration can be divided into two types: wet cave exploration and dry cave exploration.
Wet cave exploration: A wet cave refers to a karst cave with perennial underground water flow. There are two types of exploration in wet caves.
One involves free water surfaces within underground passages.
The other involves passages that are entirely flooded or use inverted siphons.
Dry cave exploration. Dry caves are fossilized caves disconnected from free water surfaces, typically developed in higher elevations over extended periods, often adorned with colorful and diverse stalactites.
A commonly used technique in cave exploration is called SRT, which stands for Single Rope Technique. This involves ascending and descending using a single rope. SRT is generally required in areas with significant elevation changes. For ascending, double ascenders are usually employed—this includes a chest ascender and a hand ascender, as shown in the image. By fixing one ascender and sliding the other, climbers can move upward along the rope. For descending, an 8-ring is typically not used; instead, devices like the STOP or RACK are preferred. These are collectively known as descenders. Ascenders, descenders, and various carabiners are collectively referred to as SRT kits, or single-rope equipment.
In addition to SRT equipment, several other categories of gear are primarily used in cave exploration, including ropes, harnesses, lighting equipment, clothing, and backpacks.
Ropes:
The main climbing rope is generally a static rope with a diameter of 10mm or more. This type of rope has a load capacity of over 20kN, making it suitable for protection. With a hundred-meter elongation of only 4 meters, it has minimal stretch, which is ideal for climbing and prevents sand or grit from entering the rope sheath due to stretching and causing abrasion.
Auxiliary ropes typically include flat webbing and Kevlar fiber ropes around 5mm in diameter, used for connecting chest and back harnesses and crafting foot loops.
Harnesses:
A harness specifically designed for cave exploration should be used. These harnesses have a simple structure, are compact, and remain comfortable even during extended wear.
Lighting Equipment (and Helmet):
A fully integrated carbide helmet lamp is recommended. Carbide lamps use acetylene gas as fuel, fixed onto the helmet, with the user carrying an acetylene gas canister on their back, connected to the headlamp via tubing. Typically, these lamps also feature a backup bulb powered by regular dry batteries for auxiliary lighting. Carbide lamps are bright and offer long-lasting illumination but are relatively expensive. For shorter or less intensive cave exploration, a high-quality headlamp may suffice. Given the risk of falling rocks and impacts, a highly protective helmet is essential—usually made of nylon fiber, which offers good resilience and excellent energy absorption upon impact.
Clothing and Backpacks:
Specialized one-piece cave suits and cylindrical backpacks designed for cave exploration are available and are waterproof. However, such specialized gear is not necessary for most cave exploration activities.
Cave Exploration Gear
1. Cave exploration helmet light: Composed of a battery-powered lamp, acetylene lamp, and helmet. For small caves, a mountaineering helmet and headlamp can be used as substitutes, but for large cave expeditions, a dedicated cave exploration helmet light is essential to avoid entering caves with harmful gases.
2. Chest harness: Use a professionally manufactured adjustable chest harness, or create one with nylon flat webbing.
3. Chest ascender: Keeps your body closer to the rope to prevent falls. Consider products from PETZL or KONG.
4. Screwgate carabiner: Must be an internationally certified (UIAA, USA, CE) screwgate carabiner.
5. Small carabiner: Used to connect the cave harness; no substitute types of carabiners should be used.
6. Cave harness: A harness specifically made for cave exploration must be used; mountaineering or rock climbing harnesses are not permitted.
7. Carabiners and quickdraws: Must be inspected and confirmed safe before use.
8. Cowstail: Reduces impact force during accidental falls. Can be DIY-made from dynamic rope with a diameter greater than 9mm, but only dynamic rope should be used. Alternatively, specialized products with better shock absorption can be chosen.
9. Carbide canister: A device that generates acetylene gas from carbide blocks and water.
10. Cave pack: Often made of PVC material, which is wear-resistant and has a smooth surface.
11. Hand ascender: Available in left-hand and right-hand versions. When in use, it should be connected to the harness via a quickdraw to prevent loss.
12. Foot loop: Can be homemade using flat webbing or an 8mm static rope. Alternatively, professional products can be used, but make sure not to use elastic dynamic ropes.
13. Foot ascender: Helps improve climbing speed and stability.
If anchoring points are used for staged descent, additional tools such as a drill or hammer, hangers, and more quickdraws will be needed.
Vertical caving techniques – An introduction to SRT
Using SRT (Single Rope Technique), there is no vertical cave in the world that cannot be descended. Currently, the deepest vertical cave descended using single rope technique reaches over 1,600 meters. SRT generally includes the following two types of equipment:
1) Rope: The lifeline of single rope technique, thus requiring very high quality. Ropes made from natural fibers such as hemp, sisal, and cotton easily rot in the damp environment of caves; while plastic ropes with low melting points and poor toughness are prone to damage from friction or free falls, making them unsuitable for caving. The currently widely used specialized caving rope is an 8–10mm diameter nylon rope with high toughness and low stretch.
Rope maintenance is very important. Before every caving trip or after returning, ropes must be carefully inspected and washed with clean water, then dried in the shade before being stored in a dedicated rope bag to eliminate potential hazards. Ropes covered in mud or physically/chemically damaged are not suitable for cavers to climb up or down. Additionally, it should be noted that caving ropes are vulnerable to cuts, fire, and must avoid contact with battery acid, lime, damaged dry batteries, gasoline, kerosene, and other solvents. During caving, ropes should not be carelessly placed on sharp rocks or sat upon.
2) Personal equipment: This serves as the bridge between the caver and the rope. Without it, one could not solo climb vertical caves dozens, hundreds, or even thousands of meters deep using just their hands. SRT personal equipment includes: harnesses (chest and seat), carabiners, descenders and ascenders, safety lines, tool bags (for placing pads, washers, anchor makers, auxiliary ropes), etc.
SRT basic techniques include:
1) Knots: The figure-eight knot is the most reliable and commonly used. It is typically required for positioning and connecting ropes at cave entrances.
2) Anchoring: At cave wall turns, anchors are set to avoid rope friction with the wall and to reposition the rope.
3) Descending: Using a descender (essentially a braking device), the caver slides down the rope from the cave entrance to the bottom.
4) Ascending: Using an ascender (essentially a one-way clamp that allows only upward movement), the caver climbs up the rope from the cave bottom to the entrance using both hands and feet.
5) Passing knots: Switching between ascender and descender, combined with the safety line, to get past anchors and intermediate knots in the rope.
6) Switching between ascending and descending mid-air: Secure the new device on the rope before releasing the old one.
It must be emphasized that when using single rope technique to descend or ascend a vertical cave, first, the rope at the cave entrance must be double-secured; second, rope friction with the cave walls must be avoided; and third, falling debris at the cave entrance must be prevented during exploration to avoid injuring cavers suspended mid-air or at the cave bottom.