Sidemount – What, why and how?

by Martin Robson PADI TecRec IT, Cave IT and Technical Field Expert for the PADI Sidemount and Tec Sidemount Diver courses.

When newer divers hear the words ‘sidemount’ many think it is a way of squirming into tight cave passages, which might not sound like fun. Or they think it is just like carrying stage cylinders, but without any back-mounted cylinders.


Neither is strictly true. Whilst sidemounted cylinders can allow suitably trained cave divers to enter caves which are too small to be dived safely in backmounts and minimise the impact they have on the cave environment, there are many and varied reasons for diving sidemount. Three years after the launch of the PADI Sidemount Diver Specialty more divers than ever are realising that sidemount is not just for cave divers but can be used and enjoyed by all divers.

The History of Sidemount

Sidemount diving has its roots in sump diving of the 50’s and 60’s in the UK. When UK dry cavers were confronted with water filled sections of the caves they were exploring they had to come up with a method of passing through these wet sections. At first they used anything they could lay their hands on, from old ‘standard dress’ equipment to WW2 rebreathers. The rebreathers they used were predominantly oxygen rebreathers so were of course limited by depth and ‘standard dress’ is not exactly streamlined so they needed a new approach. With the advent of the aqualung came a new way to break through the sumps. The size and nature of the cave passages restricted or excluded carrying backmounted cylinders, so again, cave diver inventiveness came to the fore and sidemount became the way in which UK sump diving progressed and is still used today, albeit with slightly more modern equipment!


Benefits of Sidemount

So why would you choose to configure your equipment this way?

It could be that the dive site is not easily accessible, and so carrying separate cylinders is easier than a twinset. Similarly some divers choose sidemount simply because the weight of a twinset on their backs is a little too much for them, for whatever reason.

Using double cylinders also provides the security of having a redundant system, essential for tec diving but increasingly popular for deeper recreational diving.

However, true sidemount configuration is not just like carrying stage cylinders minus the backmounts. Stage cylinders, no matter how tightly attached, can have a tendency to hang below the diver’s body a little. What we are aiming for with sidemount is to have the cylinders in line with our bodies when we are horizontal in the water and thus be nicely streamlined.

In order to do this you will need some equipment specifically designed for sidemount. Broadly speaking this equipment comprises some form of sidemount harness and a wing or other suitable buoyancy device.

There are definitely two schools of thought on these kit requirements. The American system has been developed from the combined ideas both of cave divers and more mainstream manufacturers and has evolved into what can be seen in dive shops today. Typically this would be a soft harness originally designed for back-mounts (and still recognizable as such) but adapted to mount cylinders in sidemount and to take a wing mounted to it (without the wing taking on a mind of its own under water – bear in mind there are no cylinders on your back to hold it in place). The other common option is a complete integrated harness and wing that are permanently fixed to each other.


The American systems tend to sit the cylinders ‘lower down’ when diving. By this I mean that the cylinder valve will perhaps be as low down your torso as the bottom of your ribs and if you stood up the bottom of cylinders can be as low as your knees. The other consideration with this style of equipment is that an integrated set up can weigh as much or more than a backplate and wing!

The ‘UK’ style of sidemount system has been derived from all sorts of home-made ideas generated primarily from members of the Cave Diving Group (CDG) whose foundations come from the cavers I described earlier.

These set-ups are usually less bulky and carry the cylinders a lot tighter and higher on the body to minimise the profile of the diver. Nowadays a number of commercially available harnesses and wings are on the market which follow this simple and streamlined approach. Of course with a background from dry cavers, and the need sometimes to carry kit a long way underground prior to a dive, the ‘UK’ set-ups are often very much lighter than their American counterparts. Some UK style harnesses have integral or complimentary wings, while others need a wing attachment kit to allow a wing to be fitted. This isn’t a difficult thing to achieve.


When to use sidemount.

Whatever the reason a diver wants to dive sidemount, even if it is just that it looks good, there is no need to wait for a particular dive or dive application to make good use of it, they can use it for almost all their diving.

Apart from the Sidemount or Tec Sidemount Diver course, divers can make use of sidemount on a range of PADI courses including (providing the Instructor has suitable sidemount experience) the TecRec courses.

So how do you, the Instructor deal with the student who wants to take a course and use his or her sidemount kit? On some courses, diver level knowlege for yourself and your staff may be enough.   You might find you will like it so much you want to take the next step and become a Sidemount Instructor. Sidemount Instructor (plus the relevant TecRec level) is required to teach TecRec courses to divers wearing Sidemount.

Either way, as a minimum, the instructor should be familiar with the student’s sidemount kit configuration. This is not as hard as it seems. The sidemount kit will have a buoyancy control device and two second stages just the same as a regular backmounted single cylinder, regulator and BCD set-up. The biggest difference is likely to be two first stages, one on each cylinder and two SPGs, one from each first stage, as most sidemount configurations utilise two cylinders. So apart from some extra redundancy with a second cylinder and second first stage, there is not much extra to deal with.

Dive techniques are not too different although by its very nature sidemount kit does lend itself to good body position and buoyancy control (you will have noticed this if you have had the chance to try it). There will be a minimal amount of extra work for the sidemount diver as he or she keeps an eye on both SPGs and from time to time switches from one regulator to another to balance their gas consumption from each cylinder.

Although less common, some divers use a style of sidemount with just one cylinder. It is important to remember that the single cylinder still has to have all the required components as required for normal single cylinder diving and some form of BCD. Whether single or double cylinder sidemount, equipment requirements must meet those listed in the General Standards & Procedures as well as any course specific requirements.

If you are already a Sidemount Instructor or are on the path to becoming one, how do you go about making you students feel comfortable in their new equipment and making the most of their training? Let’s take a look at some of the common problems encountered by students and how you, the Instructor, can make your students’ sidemount experience more relaxed and more fun.


So here are some training tips.

The biggest challenge new sidemount divers feel is usually all the new equipment and how it goes together. You will probably need to allow more time than you think to give the students ample time and practice getting familiar with all the new bits and pieces. We know that apart from an extra cylinder and a new way of mounting them it is essentially kit they have used before, but to the student it might not look like it, so give them time.

The same applies to their first in-water experience. The kit is unfamiliar and might feel very alien under water. Make sure that the equipment fits correctly. Take time to adjust the kit and make sure it feels comfortable. One of the most common mistakes is to have the sidemount harness too tight, making it difficult for the students to manage the kit underwater and even harder to attach or detach the cylinders. Also, be prepared for the possibility of a complete refit after the first dive as either the students become happier with their new set-up or you can see where some obvious improvements or adjustments need to be made. It is not uncommon to have two kit set-ups sessions, one before and one after their first splash.

In-water, with a little time for practice, the skills which we might think of as possibly being problematic, very rarely are. Even for newer divers, with a little coaching the skill of switching from one regulator to the other and back as they balance their gas consumption will soon become second nature. The same goes for checking their SPGs. If the kit is set up properly then access to the pressure gauges will be easy and checking them regularly will be simple.

You can help with this by making sure the students have enough time to actually dive the equipment and not just program time for the skills. Allow the students extra in-water time to get comfortable with the kit and to practice the skills you have just taught them.

Other than that, prepare to be delighted by your students’ reactions to this new set-up. Possibly looking a little daunting at first, the ease with which most students adapt and then really enjoy sidemount can be gauged by how many take the plunge and then don’t go back to their more traditional backmounted set-ups.

So if you fancy having a go, find yourself a Sidemount Instructor and jump in. The equipment may look very different, but if you try it, you might find you like it so much that you never go back to your back-mounted cylinder(s).

Martin Robson

Eurotek Gala Dinner with Martin Robson

10 Replies to “Sidemount – What, why and how?”

  1. I understand the use of sidemount for cave/wreck penetration, and even for recreational divers I can still see there not being much more risk than back mounted systems. But I am still trying to understand how sidemount follows the KISS principle in normal technical diving. You adding additional task loading with the diver having to swop regs to balance the gas in his bottom gas. Should he not do this he might have a failure in the full cylinder and then sit without any redundancy.

    So in a cave situation where we have to squeeze through narrow space I can see the trade off working, swopping regs instead of being stuck or having to remove twins underwater.

    But in normal technical diving where I am not squeezing through small space I do not see the trade off and would like to understand. What am I gaining for the additional task loading?

    1. Great question Alex. I think that, as Martin says, what is seen as additional task loading is quickly mastered. Having your valves in front of you makes valve manipulation very much easier so many sidemount divers may well think that backmount has more task loading 🙂

      1. Martin / Vikki in a cave or even wreck penetration I can see the benefit and think task loading is worth it. But in my opinion in normal tec when nothing goes wrong. Twinset only needs monitoring of 1 spg. Side-mount as I see it requires monitoring of 2 spg’s, and switching regs every 30 -50 bar, and I would assume open and closing regs a few times during the dive. As task loading goes this is a big difference. I am not talking about the deco gasses, only bottom gas.

        I am just trying to understand why people prefer the one over the other and what the mindset is for going side-mount. I am planning to try side-mount out to see for myself, but i like to think about things and to ask questions.

      2. Thanks Alex, I agree it is great to ask questions and understand your queries. I hope that when you try sidemount you like it, but if not backmount is still a great option :-). Of course, for multi-stage/deco diving there is always the option to switch to CCR….:-D

  2. Even in recreational sidemount diving, the additional task loading of which you speak doesn’t really exist. Within just one or two training dives the ‘task’ of monitoring gas supplies (physically easier in sidemount configuration than a regular backmount configuration if the equipment is well set-up) and switching regulators becomes very much second nature.

    Please bear in mind that sidemount is not just for squeezing through small spaces, even in a cave. Access to the dive site might be easier when carrying sidemount and once in the cave, cave divers take cave conservation as a matter of priority. So, we might use sidemount just to give just a better profile, have less impact on the environment (impact does not mean making contact with the cave) and allow us to use the most suitable equipment for the cave configuration.

    Overall the task loading is minimal and not something that newer divers and new sidemount divers seem to find challenging.

    Apart from when there is a real need to choose one set-up over another, I don’t think that in comparing sidemount to backmount one is inherently any more difficult than the other. Ultimately, if you find it comfortable and easy to use then why shouldn’t you? Sidemount is also quite good fun.

  3. An additional point to remember is that very few divers get back problems diving sidemount as compared with twinsets.
    Main benefit in a recreational enviroment is extended gas supply and better bouyancy control. Extra benefits are that tecrec teaches more self sufficiency and promotes better competence and confidence in a diver and their techniques and abilities.

  4. I am thinking of benefits of sidemount for older, less physically able divers with back issues etc.. Fist, the differences in the available commercial gear is confusing. I tend to prefer simple, but would you say that the simpler units are best for alum 80’s whereas the bigger more complex units are better for steel tanks? So I’m thinking simpler units for older divers. Secondly friends at my shop are vehemently critical of using sidemount for older divers because in rough seas the tanks can potentially hit people and be hard to manage. So they are saying that the switch to sidemount for older divers is actually more dangerous than traditional backmount. I don’t have a good answer for this… So is the benefit to older less physically able divers a good idea or not?

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