Helmets are a fundamental and critical piece of gear for caving. A helmet serves several key functions:
Bump protection. This may seem minor, but it’s probably the most important of all functions of a caving helmet. Caves have numerous low ceilings and ledges and anyone spending any significant length of time underground has bumped their head into a ceiling or wall more than a few times. Without a helmet it would be very easy to cause a laceration, concussion, or worse.
Falling object protection. This usually means loose rock dislodged from above by another caver, but other things can be dropped as well. This is usually a primary concern in pits or domes, but it’s also common to dislodge rocks during short climbs or on slopes.
Caver fall protection. If you slip or trip, have an out-of-control swing on rope, or take a lead-fall when aid climbing, your head may come in contact with a wall or other hard surface, and a helmet can help absorb some of the impact.
Headlamp mounting. While it’s possible to put a light directly on your head with an elastic band, a helmet provides a more secure place to solidly mount the ever-critical primary headlamp. I also recommend always having a secondary light, which can also be mounted on the helmet.
types of helmets
Caving-specific helmets are not that common, but helmets designed for rock climbing are very good options. A helmet that is UIAA rated is strongly recommended over something like a bike, ski or skate helmet. They are specifically designed to stay on the head during a fall, and are engineered to absorb the impacts of falling rocks or a climbing lead fall - the same forces that may be encountered while caving.
There are three primary helmet types: hard shell, foam, and hybrid. The helmets that are most useful to cavers are hard shell and hybrid types because they have a hard plastic outer shell that holds up to the abuses of regular caving, and provides a rigid surface for mounting a headlamp. These types of helmets are typically heavier than foam helmets, but the increased weight comes with better durability and longer life.
Hard shell helmets are almost exclusively made from ABS plastic, and they have a webbing-based suspension system to create a space between the caver’s head and the shell. Many cavers prefer hard shell helmets because there is improved air circulation and therefore better cooling, and some cavers still like to use the space under the shell to store things like an emergency trash bag. The lack of foam also makes it easier to access the inside of the helmet for drilling holes and attaching hardware for headlamp mounting. A hard shell helmet is virtually mandatory for cave diving because the foam adds unwanted buoyancy. Probably the most popular caving helmet of all time is the Petzl Ecrin Roc, but this is no longer in production. Current hard shell helmet options include the Petzl Vertex Vent, and Edelrid Ultralight.
Hybrid foam/shell helmets replace this suspension system with foam, which has excellent impact absorption properties and is lightweight. In the past most foam was EPS (expanded polystyrene), which has excellent impact absorption properties, but once it’s suffered an impact then the foam structure is damaged and the helmet must be retired. Many newer foam or hybrid helmets now use EPP (expanded polypropylene) or a combination of EPS and EPP. The EPP foam tends to be softer but it can absorb impacts and recover without permanent damage. The use of foam in a hybrid helmet allows the shell thickness to be reduced significantly, and the resulting helmets are often lighter than hard shell helmets by 10-25%. They also tend to be less expensive than either hard shell or foam helmets. Current hybrid helmet options include the Petzl Boreo, Petzl Strato, Black Diamond Half Dome, Camp Armour, and Petzl Elia (designed for women).
Foam helmets are growing in popularity with rock climbers, and are now the dominant type used by that group. They are favored because they are extremely light and excellent at impact absorption; however, if they are made from EPS then they are designed to be retired after a single significant impact. In caving, helmets are subjected to hundreds of small impacts that are likely to significantly shorten the life of a foam helmet. Some cavers still opt for these, knowing that they will have a shorter life, and use them with headlamps that use an elastic band, such as those by Zebralight, Fenix or Princeton Tec. Some popular foam helmets include the Petzl Sirocco and Meteor, Black Diamond Vapor and Vector, Mammut Wall Rider, and Edelrid Shield.