Caving
Caving—also known as spelunking by some in the United States and occasionally potholing in the United Kingdom—is the recreational pastime of exploring wild (generally non-commercial) cave systems. In contrast, speleology is the scientific study of caves and the cave environment.

Equipment
Hard hats are worn to protect the head from bumps and falling rocks. The caver's primary light source is usually mounted on the helmet in order to keep the hands free. Electric lights are most common, with halogen lamps being standard and white LEDs as the new competing technology. Many cavers carry two or more sources of light - one as primary and the others as backup in case the first fails. More often than not, a second light will be mounted to the helmet for quick transition if the primary fails. Carbide lamps systems are an older form of illumination, inspired by miner's equipment, and are still used by some cavers.
Ropes are used for descending or ascending pitches ("Single Rope Technique") or for protection. Knots commonly used in caving are the figure-of-eight- (or figure-of-nine-) loop, bowline, alpine butterfly, and Italian hitch. Ropes are usually rigged using bolts, slings, and carabiners. In some cases cavers may choose to bring and use a flexible metal ladder.

In addition to the equipment already described, cavers frequently carry packs containing first-aid kits, emergency equipment, and food. Containers for securely transporting urine are also commonly carried. On longer trips, containers for securely transporting faeces out of the cave are carried.

Safety
Caves can be dangerous places; hypothermia, falling, flooding, and physical exhaustion are the main risks. Rescuing people from underground is difficult and time-consuming, and requires special skills, training, and equipment. Full-scale cave rescues often involve the efforts of dozens of rescue workers (often other long-time cavers who have participated in specialised courses, as normal rescue staff are not sufficiently experienced in cave environments), who may themselves be put in jeopardy in effecting the rescue. This said, caving is not necessarily a high-risk sport (especially if it does not involve difficult climbs or diving). As in all physical sports, knowing one's limitations is key.

The risks are minimised by a number of techniques:

    * Checking that there is no danger of flooding during the expedition. Rainwater funneled underground can flood a cave very quickly, trapping people in cut-off passages and drowning them. After falling, this is the most likely fatal accident in caving.[citation needed]
    * Using teams of several, preferably at least of four cavers. If an injury occurs, one caver stays with the injured person while the other two go out for help, providing assistance to each other on their way out.
    * Notifying people outside the cave as to the intended return time. After an appropriate delay without a return, these will then organise a search party (usually made up by other cavers trained in cave rescues, as even professional emergency personnel are unlikely to have the skills to effect a rescue in difficult conditions).
    * Use of helmet-mounted lights (hands-free) with extra batteries. American cavers recommend a minimum of three independent sources of light per person, but two lights is common practice amongst European cavers