In terms of equipment, you may think that this new sport of SwimRun seems little more than a simplified triathlon—just minus all the bike-related gear. On closer inspection, though, there are several important differences—and what really changes things is that you will be swimming in your shoes, running in your wetsuit, running on varied terrain, and competing as a team of two. And you have the option of using various swimming aids, such as paddles and pull buoys, although, with one caveat: any equipment you start with, you have to carry to the finish line, so there are trade-offs to consider since there is an advantage to travel as light as you can. And contrary to the adherence of technical details in triathlon, the spirit of adventure racing lives in swimrun, where most of your equipment will be improvised. Consider each of these elements:

Shoes and Socks

For running shoes to work in swimrun, they will need to be lightweight, not have a tendency to hold water; they should float, dry easily, and fit snugly so that they do not come off when you swim. The stiffness of the sole and the tread will also be important considerations, since you may need stability and a really good grip, especially on sand, trails, and wet rock.

Although there are running shoes made now that are specifically marketed for SwimRun events (the official shoe of Otillø is here, and a 2016 review of these is here), you can get away with any number of regular running shoes, preferably for trail running, especially if they are lightweight, float and dry easily.

To minimize chafing, consider wearing a lightweight but snugly fitting running socks as well. A selection of swimrun socks are here, and a review is here.

For shorter events, Vibram Fivefingers may be an option, and several models are reviewed here.
Water shoes, which are made for water sports, would not have the stability or the sole for trail running and are not generally recommended.

Wetsuits

Wetsuits are a mandatory requirement for most swimrun events since they provide necessary thermal insulation in cold water, and they add the safety of extra floatation in open water.  If you are new to swimrun, you may be able to use a more conventional triathlon wetsuit, although you may quickly find some limitations to your wetsuit in this new sport.

First, conventional triathlon wetsuits were not made to run long distances in. Most wetsuits extend below the knee, but may feel very tight at the knee while running, suggesting the need to cut them off just above the knee, which is what many SwimRun competitors do. Similarly, holding your elbows at 90° while running may also feel tight during running, which would also suggest the need to improve freedom of movement with a cut off of the wetsuit above the elbow. If you have an older wetsuit, or if you can buy a cheap second-hand one that you don’t mind trimming, this would be all you need for most SwimRun entry-level events. Of course, the trade-off with cutting off parts of a wetsuit is less insulation, so you may need to think this irreversible step through carefully, depending on how cold the water will be in your event.

Secondly, there are more needs to carry things in SwimRun, and potentially to tether yourself to your partner.  So, while not critical, having some accessible pockets, and attachable points such as belt-loops to carry things may be useful. Many of the new SwimRun wetsuits will have these features built in.

And thirdly, swimrun events can be maddeningly variable in how warm you can get running in a wetsuit, or cold you might get plunging into open water.  So it is not uncommon to see SwimRun racers loosening their wetsuits while running, especially the top half, for which it would be convenient to have a front-sided zipper, and even a two-piece wetsuit to ease the loosening process when needed, including for bathroom breaks in longer events.  If the water is warm enough, some competitors may consider not wearing a wetsuit at all, or at least not the top half.

There are now several swimrun specific wetsuits available, all offering features such as zippers on both sides, the freedom to customize the length of the arms and leg components, tighter cuffs on the arms and thighs to reduce water flow into the suit, thinner neoprene over the shoulders and in the crotch to facilitate swimming and running respectively, optional two-piece versions, and some include loops and pockets.

Neoprene calf sleeves

Neoprene calf sleeves are a potentially great addition to the thigh-length SwimRun wetsuit. Since they are made with extra thick neoprene for both warmth and floatation, and they do not compromise knee movement when running, they may be thought of as an alternative to using a pull buoy and paddles, since floatation and kick are preserved. And of course, they can protect your legs when running through brush and scraping over rocks when transitioning out of the water.  Most of the same companies that make swimrun wetsuits also make these products, often in different weights (degrees of floatation).

Goggles

Goggles have been used for decades by open water swimmers and triathletes--to help with sighting, and to protect the eyes from cold water exposure the irritating effects of salty water, and potentially other hazards in the water. Goggles can also help tremendously with glare, reflections, and bright sunshine, when equipped with tinted, mirrored, or polarizing lenses.  Prescription lenses are also available at some optometry offices.

Some swimrun competitors will use somewhat larger (than pool use) goggles, to provide more face cover from the cold, and to provide a larger lens to sight with, especially in choppy, murky waters. However, many of these have only a single air-filled compartment, so one gasket leak will affect both eyes.

The most important feature, though, is that they fit well, and will not start leaking in a long event like swimrun. Make sure the goggles you choose seal well over your face, are comfortable over long periods of use, and have only been lightly used (the gasket is still pliable). Once you have found the best fitting goggles for your face, consider buying several pairs, with different lenses to adapt to different conditions.

During an event, some racers carry an extra set, in case of loss or damage. However, newer goggles, are less likely to fail. Keeping them on your head while running should prevent losing them on a trail, especially if you have put the straps under your swim cap.

Avoiding the fogging up of goggle lenses is also critical for prolonged and repeated swims ( a much different consideration than in a triathlon, so you will need a reliable strategy to avoid losing your vision, especially on grey, cloudy or misty days. There are several sprays and wipes available, although just rinsing them in water when starting a swim will work fine; alternately, using saliva, or baby shampoo are other common insider tricks. Sometimes just using a new pair of familiar goggles on race day will be sufficient. Different brands of goggles have different lens and finish qualities that may make some of them resistant to fogging up for whole day events. Try some of these strategies during training to see what works best for you.

Swim cap

Although most triathlon and swimrun events will supply you a race day swim cap, these are usually a latex cap, which are numbered to identify you. However, when your swim is anticipated to be in colder water, especially below 15°C, having a secondary silicone cap (which is stronger and thicker) underneath the latex cap may be prudent to better insulate your head. And in waters approaching 10°C, a thicker, neoprene cap can also be worn underneath your race cap-- these will provide some extra protection of your cheeks and neck as well.

Swim caps used in open water should always be brightly colored, to keep you more readily visible to watercraft.

Earplugs

Since very cold water can stimulate the balance center in your middle ear, causing dizziness and disorientation, some swimmers use earplugs while swimming to lessen this effect in cold-water swims. This is often worse if one ear gets cold water in it, while the other does not. However, earplugs can be irritating to have in the ear canal for hours, and obviously interfere with hearing while running, and they would be easy to lose if you took them out during runs--all trade-offs to consider when racing or training.

Pull-buoy

Since swimrun events require you to swim in your running shoes, most swimruns allow floatation aids to compensate for the tendency of your feet to sink with running shoes on. Pull-buoys (made of polyethylene foam) are commonly used in swimruns for this purpose, being held between your thighs to provide leg buoyancy. However, in a swimrun race, you will have to carry them while running. To help with this, they have been easily customized to be attachable to either your thigh or to a waistband. There are now several YouTube videos demonstrating different attachment and carrying techniques, such as one made by Head, here.

To customize a pull-buoy, simply drill some holes through it (see the instructional videos), and then insert rubber or elastic straps through grommets to make a loop that you can attach to your upper leg. Stretchy cord or used bike inner tubes are inexpensive and readily available, and plastic wall plugs can serve as grommets.  Be sure to test it well, both in the water and running before a race – if it’s too tight it will be uncomfortable and may restrict thigh blood flow, too loose and it will twist around and slip down inconveniently, either in a swim or while running.

Hand paddles

Since the use of pull buoys compromises propulsion from kicking, most SwimRuns also allow the use of hand paddles (they are not, however, a requirement). These add some extra power to your strokes by increasing the force of the ‘catch’ phase of your swim stroke, but will quickly overwhelm your shoulders and arms if you haven’t trained with them in distance swims. Although there are many styles of paddles on the market, you’ll need some that float and have straps to hold them on your hand—otherwise you will risk losing them as they sink in open water.  When competitors get out of the water, they will either rotate the paddles so that they sit on the back of their hands, or take them off and carry them on their waist belt.

If you decide on using paddles for racing, you will need to distance train with them, including in open water, to develop a tolerance for them. When you have paddles on your hands, it is difficult to use your hands for anything else, whether potentially adjusting your goggles, your wetsuit, or your pull buoy, climbing over rocks, or accessing any other gear you may have with you. They can be useful, though, when your hands lose strength or water feel when cold, preserving the catch phase of your stroke. Depending on the distance of your swims, shorter, smaller paddles may be preferable to avoid shoulder injury. Or, consider webbed gloves instead, which would be easier on your shoulders and provide more thermal protection.

Gloves

Wearing neoprene gloves, especially if they are webbed, may be a reasonable alternative to paddles, especially in cold water, as long as they do not fill with water. As mentioned, they are less likely to overwhelm your shoulders while adding some increased surface area for the catch. Like swimming with paddles, these take a bit of getting used to and can slightly increase the resistance of your ‘catch’ in the water. They can also make you feel clumsy if you need your hands for anything, as described above.

Fins
The use of fins/flippers is allowed in most swimruns (check with the rules or the race organizers), although they may be difficult to put on while wearing running shoes. While they can provide a significant amount of propulsion, they may also wear out your legs more for running, and may be hard to carry especially while running in challenging terrain. Practice using them in training before deciding if the trade-offs are worth their consideration. Most swimrunners in longer events do not use them.

Personal Swim Buoys

As a safety tool (especially with a whistle attached), the personal swim buoy (PSB) is recommended equipment in some swimruns and some open water swim events. It is an inflated, brightly colored safety aid connected by a short tether to a belt and towed behind the open water swimmer. They come in various sizes, and some have an internal dry bag to carry various belongings, including cell phones, keys, clothing, first aid kits, maps, hand paddles, and/or food. Since many longer swimruns have a mandatory equipment list, it may be necessary to consider how to carry a lot of items conveniently, like cell phones, maps, food, hand paddles, gloves, and first aid kits, so a PSB may become an important consideration.

Because they use air chambers that are theoretically vulnerable to deflation (most have dual chambers to reduce this risk), they are not considered a life-saving device, although they can provide floatation if needed, for resting or awaiting assistance. They can easily allow even a large-sized man to keep his head above water.

When swimming with a PSB in tow, it is surprising that they do not seem to create drag, unless swimming in strong headwinds or if they are exceptionally loaded down. They are positioned to sit above the backs of your knees while swimming, just out of reach of your stroke finish, and out of the way of your kicking movements. It appears that the bow wave created by your shoulders creates an eddy behind you that actually pushes the PSB forward.

Besides their storage capabilities for essentials, and their ability to provide floatation, PSBs provide other important safety features: they allow a swimmer to become more visible to watercraft; they improve the ability of coaches, lifeguards, and race support crew to monitor swimmers in open water, which can be dark, cold, windy, and choppy. PSBs can easily attach a whistle for emergencies, and they can also easily carry a small light inside the dry bag portion that can be turned on in semi-dark swims, causing the PSB to glow. Most PSBs have a quick release belt clip, which can allow one swimmer to easily give it to another swimmer in distress.

Before using a PSB in a SwimRun event, practice using one in training, to consider how you are going to carry it while running, and what you might load it up with or attach to it.

Whistle

Some longer swimrun races require each competitor to carry a whistle for emergencies.  These can be attached to a PSB (as described above), or put on a lanyard to be worn around the neck, under a wetsuit.  They could also be attached to the wrist or to a glove. Effective whistles should be metal or plastic, and should be easily cleared to work in water--always test them ahead of use in an event.

Tether Line

Some swimrun events require teams to stay within 10 meters of each other, in part for safety reasons to look after each other. Because it is easy to drift in different directions in a swim, especially when partners have different swim and sighting abilities, a tether line can keep pairs together, and can allow the weaker swimmer to draft or be towed by the stronger swimmer, an effect that can also be created in the run.

Tether lines are usually elastic, with carabiners at either end, and cannot be more than 10m in length. At times you may want or need to disconnect it, so one team member has to carry it (especially on the first run leg, where many competitors are crowded together). You may need to strategize how and when you are going to use it, and you would definitely need to practice using it before a swimrun event, since you can get tangled up in it. There is no ideal length, although many are about 3-5 meters long.  If you want to make your own, here is a quick demo, or check out these options.

If you are both using a PSB, then you both have a waist belt to attach a carabiner to, although it can be clipped to itself.  Alternately, some swimrun wetsuits have loops specifically for this purpose, for easy attachment of the tether.

Food and Drink

Although Aid Stations are usually spread over a SwimRun course, with various nutritional offerings that you should be familiar with before you start your race, gels or bars or even small water bottles may be considered as part of your carried equipment, as long as they are waterproof, lightweight, and easily accessed. Consider storing these items in your PSB, or have items attached to your belt or tucked in a pocket or under a part of your wetsuit (some athletes are known to stick a gel up and under the lateral side of the wetsuit thigh). And of course, do not discard anything on the course--always carry your litter with you, until the next aid station, where there is usually a trash can.