I still remember watching a swimrun race a few years ago and seeing an athlete cross the finish line with a wetsuit that looked like it had been through a lawnmower. The legs were hacked off unevenly, there was duct tape holding a torn shoulder together, and the zipper was tied open with a shoelace. He'd been on the course for over four hours, alternating between swimming through cold, choppy water and scrambling over barnacle-covered rocks. His homemade solution had gotten him to the line, but just barely. That image stuck with me because it perfectly captured what early swimrun athletes had to do-make do with gear that was never designed for the sport they loved.
Swimrun was never supposed to be a gear-intensive sport. Born on a bar-hopping challenge between islands in Sweden's archipelago, the original idea was simple: swim a bit, run a bit, repeat, using whatever you had on your back. But as the sport grew from a handful of adventurous friends into a global racing community, it became painfully obvious that cutting up a triathlon wetsuit with kitchen scissors wasn't going to cut it anymore. The demands of swimrun are fundamentally different from pure swimming or triathlon, and they demand a fundamentally different kind of wetsuit.
Why Swimming Wetsuits Fail on Land
A traditional triathlon wetsuit is a marvel of engineering-for swimming. The long legs lift your hips into an ideal position in the water, the high collar seals out cold, and the carefully calibrated buoyancy helps you glide through each stroke. But the moment your feet touch solid ground and you start running, that same design works against you in ways that range from annoying to race-ending.
Let's break down what actually happens when you run in a full-length suit:
- Overheating kicks in fast. Neoprene holds body heat beautifully in 60°F water, but start a 5K trail run in the sun and you'll feel like you're jogging in a sauna. Your heart rate climbs, your sweat pours, and before you know it, the swim leg's energy savings are wasted trying to cool down.
- Your stride gets chopped. Long neoprene legs don't just feel restrictive-they actually resist your natural hip extension and knee drive. Every step becomes a little battle against the material, taxing your hip flexors and subtly changing your running mechanics. Over multiple run segments, that extra effort compounds.
- Chafing moves from nuisance to real problem. In the water, you barely notice seam contact. On a dry trail, the repeated rub of neoprene against skin can create hot spots within minutes. Salt and sand from swim exits make it even worse.
- The suit falls apart. Swim wetsuits are built for smooth, repetitive arm motions and minimal abrasion. Run through scrub, scramble over granite, or brush against a rocky shoreline, and you're asking tears, seam failures, and punctures you'd never see in an open-water swim.
None of this is the suit's fault-it was simply asked to do a job it wasn't engineered for. That's why blueseventy decided to build the Alliance: a wetsuit that treats swimrun not as a weird offshoot of triathlon, but as its own demanding discipline.
The Blueseventy Alliance: Designed with Both Sports in Mind
When we sat down to design the Alliance, we didn't start with an existing tri suit and ask, "What can we cut off?" That's the approach that leads to uneven hems and busted seams. Instead, we started with the athlete's movement: how you swim efficiently, how you run naturally, and how you transition between the two a dozen times during a race.
Free Your Knees, Free Your Stride
The Alliance's short-leg cut ends above the knee, completely clearing the joint. It's not a compromise-it's a deliberate choice that lets you run with your full natural gait. Whether you're charging down a coastal trail or grinding up a steep climb, there's no drag on your legs from neoprene that's trying to yank your hips back into a swimming position. That means less fatigue, better turnover, and a chance to actually enjoy the running portions.
Vent When You Need It, Seal When You Don't
The full-length front zipper is the Alliance's secret weapon. The moment you emerge from the water, unzip it and you instantly dump heat. Run with the suit open like a vest and your core stays cool, even on exposed trails in full sun. Then, right before the next swim entry, zip it back up and you've got a smooth, hydrodynamic front that won't scoop water or drag. Some athletes even rig a small lanyard or clip to keep the zipper pull from bouncing on the run, though the suit's design keeps it pretty well behaved on its own.
Built Tough Enough to Take a Hit
We used a more durable neoprene and reinforced seam construction for the Alliance because swimrun surfaces are unforgiving. The outer fabric resists tearing on rock faces, roots, and the boot-scramble sections that define the best courses. I've watched athletes run the Alliance through waist-deep rocky shallows, scrape along barnacle-encrusted retaining walls, and flop over driftwood-and the suit holds up. That durability isn't just nice to have; it's peace of mind when you're miles from the nearest aid station.
Buoyancy That Works in Two Worlds
In the water, buoyancy equals speed. A suit that lifts your hips and legs close to the surface reduces drag and conserves energy. But if you put too much buoyancy in the legs, you can actually mess with your running rhythm-your feet feel unnaturally light and your kick timing gets thrown off. The Alliance concentrates buoyancy in the torso and hips, where it does the most good for your swim position without making your legs feel disconnected from the ground. You'll finish each swim segment feeling fresher, and you'll hit the trail with your normal running cadence intact.
A Warranty That Actually Covers Your Race
Here's something no one tells you: most wetsuit warranties are void the moment you run in the suit. Seriously. If you buy a triathlon wetsuit and then compete in a swimrun, you're on your own if the seams blow out or the material tears. The Alliance is different. Blueseventy's one-year manufacturing-defect warranty specifically covers swimrun use-it's the only suit in our line with that explicit guarantee. We can offer that because we built it for exactly the beating it's going to take.
For women, the Alliance incorporates Femme Fit-our 15-plus years of refining how a wetsuit should fit a female athlete. That means a lower neckline that reduces chafing, an extended zipper for easier entry and faster transitions, and a pattern cut through the bust and hips that actually moves with you on the run. A poorly fitting suit becomes agony during multi-hour swimrun; Femme Fit ensures the suit works with your body, not against it.
Getting the Right Fit (and Keeping It Alive)
The golden rule for any blueseventy wetsuit is that it should feel snug on dry land and significantly more comfortable once you're in the water. With a swimrun suit, you need to add running motion to that test. Put the Alliance on and move around your living room: high-knee marches, arm swings, a few jumping jacks. The suit shouldn't slide down, bunch in the shoulders, or bind across your back when you rotate your torso. If you're between sizes, err toward the one that gives you the most shoulder and hip freedom-you'll thank yourself at mile 12.
Don't forget the Test Swim policy, either. You can actually take the Alliance for a swim (and a run) before you commit, as long as you return it clean, dry, and with tags attached within 30 days. That's huge for swimrun, where the fit has to work for two very different activities.
After your race-or even a solid training block-give the suit a thorough freshwater rinse. Salt, sand, and grit will work into the neoprene and zipper over time, so don't skip this. Hang it inside-out to dry first, then right-side out, well away from direct sunlight. A little silicone-based lubricant on the zipper every few uses keeps it gliding smoothly. And if you do get a small tear from an unlucky rock encounter? Aquaseal neoprene cement (right from blueseventy.com) will fix it fast, though the Alliance's reinforced build means you'll reach for that tube less often than you might expect.
Ready to Take on the Archipelago?
Swimrun is one of the purest, most ridiculous, most beautiful endurance challenges out there. It deserves gear that rises to the occasion-gear that was built from the ground up to handle the unique chaos of swimming and running over and over again. The blueseventy Alliance, at $275, is that suit. It's the only one in our lineup purpose-built and warrantied for swimrun, and it exists because we believe every product should help you chase your personal best, no matter how many times the landscape shifts between strokes and strides.
Find your size at blueseventy.com, or use our store locator to try one on in person. Take it for a test swim, a test run, and then go get gloriously lost between islands.
Happy swimrunning!
