Caver

Safety

• 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. In the UK, drowning accounts for almost half of all caving fatalities (see List of UK caving fatalities).
• Using teams of several cavers, preferably at least four. 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 organize 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 among European cavers.
• Sturdy clothing and footwear, as well as a helmet, are necessary to reduce the impact of abrasions, falls, and falling objects. Synthetic fibers and woolens, which dry quickly, shed water, and are warm when wet, are vastly preferred to cotton materials, which retain water and increase the risk of hypothermia. It is also helpful to have several layers of clothing, which can be shed (and stored in the pack) or added as needed. In watery cave passages, polypropylene thermal underwear or wetsuits may be required to avoid hypothermia.
• Cave passages look different from different directions. In long or complex caves, even experienced cavers can become lost. To reduce the risk of becoming lost, it is necessary to memorize the appearance of key navigational points in the cave as they are passed by the exploring party. Each member of a cave party shares responsibility for being able to remember the route out of the cave. In some caves it may be acceptable to mark a small number of key junctions with small stacks or "cairns" of rocks, or to leave a non-permanent mark such as high-visibility flagging tape tied to a projection.
• Vertical caving uses ladders or single rope technique (SRT) to avoid the need for climbing passages that are too difficult. SRT is a complex skill and requires proper training and well-maintained equipment. Some drops that are abseiled down may be as deep as several hundred meters (for example Harwoods Hole).