Sidemount versus Backmount

By Natalie Gibb

When I started cave diving, everyone used backmounted doubles, so I did, too. I swam around with my head crooked sideways pressed against my manifold, neck cramping, and bruises on my calves because double aluminum 80’s are basically taller than I am and they banged into my legs when I walked to the water. There weren’t a lot of 4’11” (150cm) cave divers in Mexico at that point, and I didn’t have any real options. I spent the first four years of my cave diving career schlepping around twin tanks that were significantly heavier than I am, but I don’t regret it because it made me comfortable with the configuration.

Traditionally, cave diving has been taught in backmounted doubles, and I still feel that proficiency in the configuration is necessary for those working in technical diving. Even ten years ago, teaching entry-level cave diving in sidemount was considered risqué: the gear was homemade and there were no official training programs or standards for sidemount cave diving. Nowadays, you’re just as likely to see cave courses being taught in sidemount as in backmount, and that leaves beginning cave diving students with a choice. So what’s it going to be: backmount or sidemount?

You are not marrying your equipment configuration 

Both backmounted doubles and sidemounted doubles have their benefits and disadvantages. I dive primarily sidemount, but I do not believe that it is necessarily the better equipment configuration for every diver. Whichever gear you end up choosing, realize that you are not locked into that choice forever. Should you decide that you want to switch from backmount to sidemount or (gasp) vice-versa, you can do a cross-over course.

Regardless of the configuration you ultimately choose, you will need fundamental skills training. Diving into flooded caves requires excellence for survival, and there are no shortcuts. The journey starts with honing your base skills, and this requires training and time in the water. These skills include buoyancy and trim, long hose air sharing, valve shutdowns, and propulsion techniques. For sidemount, proper fundamentals training should also include skills such as hardware failure.

And here’s the gist – fundamental skills are different in backmount and sidemount. The way you hold your body, the method of finning for ultimate efficiency, balance – these all change with configuration. Beware of any instructor who accepts you straight into cave course without insisting that you have technical-level foundational skills training on it first. Even the best divers cannot master a new configuration and a new environment at the same time. Details of both will be lost and the diver will be weaker for it. Take your training stepwise and gain experience at each level, starting with fundamental skills in your configuration of choice.

It depends on the diver

Tiny people will generally be more comfortable cave diving in sidemount. It’s not the hassle of lugging heavy doubles to the water, the ability to reach valves, or to difficulty of managing gear that is larger than one’s body; speaking from personal experience, these can all be done with practice and technique. The main reason is more fundamental – short people will have difficulty looking up and forward using backmounted doubles because the manifold and tank position prevents it. There is no way to lower the tanks away from a small diver’s head without impeding his ability to kick. In cave diving this is a safety and conservation issue – divers who cannot comfortably maintain at least peripheral vision of their team and the cave ceiling will have impaired environmental and situational awareness, and inherently will be less safe.

Divers who are already experienced with backmounted doubles may choose to enroll in cave training using their familiar equipment configuration. This includes divers who have experience in wrecks and those who have taken technical diving courses. There is no need to reinvent the wheel here. Divers who own their own gear and are comfortable in it are often happier simply focusing on learning to dive in the cave as opposed to increasing their task loading with new gear.

Sidemount does have some advantages in comparison with backmount, including the ease of moving tanks to the water. Divers using a sidemount configuration can easily view and access their tank valves and first stages, which streamlines the process of assessing and solving problems. The first stages and tank valves are protected by the diver’s shoulders, which means that the chance of knocking a piece of vital life support equipment against the cave is lower (although cave divers should not be banging into the cave accidentally in any configuration). And of course, sidemount is truly redundant, meaning that there is no single failure that can cause a total gas loss. However, keep in mind that diving without a manifold means that in the event of a regulator failure, the sidemounter loses access to half his breathing gas.

Backmount is by far a simpler configuration for the beginning doubles diver. In sidemount there are more methods of solving problems and equipment failures, and to be proficient in sidemount the student must learn them. For this reason, sidemount fundamentals courses can, and should, take longer than backmount fundamentals courses. From a safety standpoint, while there are a few (vanishingly rare) failures that can cause a total gas loss in backmount, the configuration has the advantage that the loss of a regulator does not mean that the diver loses access to half his breathing gas. It is possible to breathe from both tanks with either one of the regulators, or shut down the isolator valve and save half the breathing gas if one tank is hemorrhaging. In either configuration, the diver still has his buddy as a source of emergency gas and gear. No one should be solo diving as a new cave diver.

Keep in mind that you can still dive with friends who use a different configuration from you. I don’t believe that mixed teams are bad. A proper, modern cave course should review both equipment configurations and prepare divers to gear match, gas match, air share, and dive with divers in a different configuration. It’s silly to limit your buddies simply because they like to wear their tanks on their backs or on their sides, and it’s always possible that you will encounter a diver in a cave someday who need assistance and happens to be using a different equipment configuration than you are. Safe cave divers need a basic understanding of how both configurations work, even if they only dive one.

Other considerations

A philosophy of “mission-specific sidemount” exists. The concept states that backmount is the preferable equipment configuration for all dives except those requiring a sidemount configuration – in other words, very tight caves. I disagree with this idea because I feel that a diver should be intimately familiar with his equipment in advanced cave environments. This requires time in the water and years of familiarity to do correctly – not a short series of warm up dives. If your goal in cave diving is to enter extremely tight caves one day, then I would suggest starting in sidemount from the very beginning, to maximize your in-water time with the equipment. Divers should still log hundreds, if not thousands, of cave dives and enroll in advanced sidemount training before entering extremely tight caves.

Most people who take up sidemount cave diving use it in big open places that a backmount configuration can also fit into. Very few recreationally accessible caves truly require sidemount configuration. In fact, there are definitely places where it is easier to fit with backmounted tanks (such as narrow canyons). Backmounters go into very tight caves as well – they just remove their doubles to fit. This requires advanced cave training in backmount but guess what… sidemounters should also take advanced cave training if they want to remove tanks to fit into places. I would count it as a disadvantage of sidemount that the configuration enables divers to enter tight places before they are ready or trained to do so. Choose sidemount for its logistics and comfort, if they appeal to you, but save tight caves for your advanced cave diving career.

Choose what makes sense for you

Backmounters call sidemounters trendy, and sidemounters call backmounters antiquated. This is silly. Let’s lay off the attitude. Your equipment configuration is a personal choice. It is a tool that you will use to go some of the most awe-inspiring, remote diving in the world. But it’s just that, a tool. Each budding cave diver should take a look at the pros and cons of the configurations, and make his choice based on his comfort and preference. At our shop, we offer a day of demos – backmount and sidemount – to help divers make this decision. Ask your cave instructor to let you try out a few different configurations and go with what feels right. 

Natalie Gibb Is a full cave instructor, explorer, and researcher based in Mexico’s Riviera Maya. She is a published author, international speaker, and cave conservationist. For more visit: www.underthejungle.com