Without a helmet you will soon bang your head at the least, at worst a fall or rockfall could result in serious, even fatal injury. The helmet should be capable of protecting against both falling objects and protect the wearer in the event of a fall, in either case the chinstrap should retained the helmet on the head. Industrial helmets without modification are totally inadequate, they are too easily knocked off in a fall. Helmets should have a four point fixture chinstrap and if a modified industrial helmet is used it should be to British Standard 5240, D.I.N. 4840, CE. or local equivalent, the highest standard protective helmet for industrial use. For instructed caving and where a caver is employed or self employed Personal Protective Equipment regulations apply.
Caves vary considerably in their internal climate.
Some caves in the U.S.A. are dry and relatively warm, while most U.K. and other European caves are cold and wet. The following information applies to the U.K. and is applicable to many other caving regions. In the past many caves were done in nothing more than old, warm clothes and overalls. This is a recipe for hyperthermia in all but the simplist and dryest caves. In any case a set of waterproof clothes should be worn over warm and non restrictive clothing.