Open water swimming is becoming more popular as a key part of triathlon and long-distance swim races.
One of the most talked-about spots lately is the Seine River in Paris, where Olympic triathletes took the plunge during the 2024 Paris Games.
Swimming in a river like that is a special experience. It feels raw, real, and totally different from laps in a pool.
Of course, river swimming comes with its own set of challenges: currents, visibility, and water quality, to name a few.
Still, many athletes love the thrill. There’s something freeing about swimming in nature: the open space, the current, even the occasional fish brushing past.
Here, I share some thoughts on the joys and challenges of open water swimming that might be interesting for triathletes.
Challenges of Open Water Swimming
According to the stats from Triathlete.com, river swims are relatively rare in triathlon races. Only about 11% of full-distance events feature them.
Lakes and reservoirs are more prevalent, and they make up nearly half of Ironman swims. For 70.3 races, ocean swims are the most common as they comprise 38% of events.
Still, when rivers are part of the course triathlon swimming portion, they bring a very different kind of test. The dynamic environment adds unpredictability that can’t be replicated in a lake or ocean.
River swims can be beautiful and exciting, but they also come with a few surprises you won’t find in a pool or calm lake. Here’s what to watch out for:
Currents and drag
The flow of the river can either help you or work against you. Swimming downstream feels fast and fun, but going upstream can be a grind.
It takes more effort and smart pacing to avoid burning out early by trying to fight the current. That is why learning to adjust your stroke and breathing rhythm is key. The speed of river swims can vary significantly depending on the current.
For example, during the Oregon 70.3, athletes have reported significantly faster swim times due to strong downstream currents. Some swimmers noted they finished the swim leg in under 20 minutes, compared to their usual 30+ minute times in other settings.
On the flip side, races like Waco 70.3 show that river swims don’t always offer an edge. Many athletes there noticed little to no help from the current, with swim times ending up pretty similar to lake or pool races.
Debris and obstacles
Rivers are full of natural surprises. You might swim past floating sticks, tangled weeds, or even bump into a rock or two. Every now and then, you could spot a fish or feel one glide past your leg. It’s all part of the adventure, but it means you need to stay alert and be ready to adjust your line.
Limited visibility
Unlike crystal-clear pools, river water can be murky, especially after rain. That makes it harder to see where you’re going, draft behind other swimmers, or spot the next buoy. To stay sharp, make sure you practice sighting: lift your head regularly to check your direction.
Crowded starts
River swim starts can feel more chaotic than usual. Narrow spaces mean lots of bodies close together, especially in the first few hundred meters. It’s easy to get jostled or lose your rhythm.
If you’re not comfortable in the middle of the pack, consider starting slightly to the side or behind the main group.
Temperature shock
Some rivers run cooler than you’d expect, especially early in the morning. Hitting that cold water can take your breath away, literally. It can also tighten your muscles if you’re not warmed up properly.
That’s why it helps to get in early for a short warm-up and get used to the temperature before the race begins.
Open Water Swimming During Triathlon Events
The swimming portion is around 10% of the race time. But in long-distance triathlon competitions like Ironman, this is a challenging start that can set the tone for the rest of your race.
- Swim: ~1 to 2 hours
- Bike: ~5 to 7 hours
- Run: ~3 to 5 hours
- Total time: ~10 to 15+ hours
And, let’s be honest, this part of the race is no walk in the park. Swimmers have to deal with unpredictable conditions: strong currents, choppy waves, and sometimes not-so-great water quality. It’s a real test of both physical and mental strength.
Success in marathon swimming races requires solid technique (SWOLF swimming is a helpful way to improve your technique), good navigation skills, and smart energy management. One wrong turn or early sprint can cost you later in the race.
Places like the Seine River, where Olympic triathletes competed, offer stunning but tough race environments. They push athletes to stay sharp and adapt quickly.
Men’s triathlon swim times (Average):
- Seawater: 1,134.83 seconds (~18:55)
- River: 1,182.68 seconds (~19:43)
- Stillwater (lakes/reservoirs): 1,155.82 seconds (~19:16)
Women’s triathlon swim times (Average):
- Seawater: 1,246.45 seconds (~20:47)
- River: 1,234.5 seconds (~20:34)
- Stillwater: 1,229.72 seconds (~20:30)
These figures suggest that, on average, river swims are slightly slower than lake swims but faster than ocean swims.
Tips and Strategies to Prepare for Open Water Swims
Preparing for open water swims in triathlons requires specific training and strategies to handle unpredictable conditions like currents, waves, and crowded starts. Here are key tips to help you succeed:
1. Get comfortable in open water
Practice in similar conditions: in lakes, oceans, or rivers. This will help you adapt to cold water, waves, and limited visibility.
Elevate your sighting skills. Lift your head every few strokes to navigate buoys efficiently (practice in a pool with landmarks).
If allowed, train in your wetsuit to adjust to buoyancy and restricted shoulder movement.
2. Master race-specific skills
I’m talking about:
- Drafting: Swim close behind or beside another swimmer to save energy (like cycling drafting).
- Mass start: Simulate crowded conditions by swimming with a group to handle contact and chaos.
- Bilateral breathing: Breathing on both sides helps with sighting and adapting to waves.
3. Build endurance & speed
- Long swim sessions: Increase distance gradually to build stamina (e.g., 10-20% longer than race distance).
- Interval training: Mix sprint intervals (e.g., 50-100m fast) with steady-paced swims to improve speed.
- Brick workouts: Follow open water swims with short bike/run sessions to adapt to transitions.
Race-Day Strategies
If the organizers allow it, take a few minutes to get into the water before the opening ceremony. A short practice time helps your body adjust to the water temperature, especially if it’s colder than expected. It also calms nerves and gives you a feel for how the water moves: current, temperature, and even how your wetsuit feels.
Nerves are normal, especially at the start. If you feel overwhelmed or panicked, don’t try to push through. Instead, roll onto your back and float. Take deep breaths and let your heart rate settle. You won’t lose much time, and it’s better to reset than to burn out or pull out. Most swimmers only need a few seconds before they’re ready to keep going.
If it’s a cold-water swim and you’re wearing a wetsuit, pour some water inside it just before the race starts. It’ll feel chilly for a moment, but it helps your body adapt more quickly and reduces the shock when you dive in. Some athletes even splash water on their face and neck during warm-up to prep their body for the cold.
Gear сhecklist for open water swimming
- Wetsuit (if water is cold) – practice removing it quickly for T1.
- Goggles (tinted for sun, clear for overcast days + a spare pair).
- Swim cap of a bright color for visibility.
- Anti-fog spray for goggles.
Also, make sure you check out this full triathlon race-day checklist to ensure you have all the essential items.
