Published September 23, 2025 06:00AM
6 Things to Look for in a Race to Avoid a Canceled Swim
Before you sign up for your next triathlon, make sure the swim won't be scrapped. Here's what to check to avoid a disappointing duathlon.
(Photo: Jose Luis Hourcade/Challenge)
For most triathletes, the swim leg sets the tone of the day. Whether you love or dread it, nobody signs up for a triathlon hoping to do a duathlon instead. But in recent years, canceled swims have become more common, usually due to water quality issues, weather, and safety logistics.
Know that these cancellations are actually for athlete safety, not just because race directors are being overly cautious or are simply covering themselves legally. We’ve seen swims that should have been canceled pose very real risks: At the 2024 edition of Ironman 70.3 Morro Bay, unusually strong tidal currents in the bay led to nearly 200 swimmers having to be actively rescued, and at the 2023 Ironman 70.3 Cork, athletes swam a shortened course after Storm Betty battered the Irish Coast, but swimmers still faced huge waves and rough seas, causing athletes to panic in the breakers. Adverse conditions can turn what should be a controlled swim into something dangerous, both for athletes and safety volunteers. Add in other examples, like outbreaks of GI illness after races held in polluted water, and it’s clear that canceled swims are about preventing avoidable emergencies and keeping athletes safe.
While no athlete can guarantee a race will go off exactly as planned, you can stack the odds in your favor by being a smart consumer when choosing an event. Here are six factors to consider when evaluating a race if you want to maximize your chances of getting in the water on race day.
1. History of canceled swims
Before signing up, do a little homework: Has this event had swim cancellations in the past? Races held in the same venue year after year often face recurring challenges – whether that’s a river prone to flooding, a lake susceptible to algae blooms, or coastal conditions that whip up heavy surf. A quick Google search or scan through race reports will tell you if the swim has been canceled or shortened multiple times. While one-off cancellations can happen anywhere, a repeated pattern may indicate that the venue carries inherent risks.
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2. Water quality and pollution concerns
One of the leading reasons swims are canceled is poor water quality. Urban rivers, harbors, and lakes downstream of agricultural land can experience spikes in bacteria, especially after heavy rainfall. Many municipalities test water quality regularly, and those results dictate whether permits are granted. If you’re choosing between venues, a clean mountain lake or ocean bay with strong tidal flushing may be less risky than a stagnant or urban waterway.
A growing issue is harmful algal blooms, often linked to warming water temperatures and nutrient runoff. Algae can release toxins that are dangerous for swimmers. If your target race is scheduled in the peak of summer in a warm, shallow lake, know that this could be a wildcard.
3. Weather and seasonal timing
Mother Nature plays a big role. In some regions, severe weather is a predictable factor at certain times of year. Thunderstorms are a prime culprit: Lightning in the area means an automatic no-go for safety reasons – water conducts electricity, and if lightning strikes the water, the charge can spread across the surface, causing injury or even death. Races held in the Southeast or Midwest during late spring and summer are more vulnerable to storm-related delays or cancellations.
Cold snaps can also make water temperatures unsafe, especially for early season races in northern climates. On the flip side, drought conditions in the West have lowered lake levels, making some swim courses too shallow to safely set buoys. When selecting a race, consider the seasonality of the venue and whether it aligns with reliable conditions.
4. Tide, current, and surf exposure
Ocean swims are thrilling, but they come with additional risks. Big surf, rip currents, or strong tidal shifts can lead race directors to shorten or cancel swims. Protected bays and coves are generally safer than open-ocean beaches, which are more exposed to swells and changing tides. Similarly, river swims may be canceled if currents are dangerously fast after rainfall or snowmelt. While you might think a fast current would actually be a nice assist to swimmers, it makes the swim dangerous – fast water can sweep athletes sideways, funnel them off course, or carry them into unsafe areas, like docks or boat channels, and make it harder for rescue crews to reach them. If you’re less comfortable with unpredictable water, look for venues with sheltered conditions.
5. Race size and safety resources
A smaller race with limited safety personnel may be quicker to cancel a swim at the first sign of questionable conditions because organizers simply don’t have the resources to manage higher risks. Larger, well-established races often have extensive safety protocols in place: multiple lifeguards, paddleboards, jet skis, and medical staff. While more support doesn’t mean a swim can’t be canceled, it may provide organizers with more flexibility to manage marginal conditions rather than pulling the plug altogether.
6. Local regulations and permitting
Race directors must comply with local permitting authorities, which often set stricter thresholds than athletes might expect. For example, a city health department may cancel a swim due to elevated bacteria counts even if athletes claim the water looks fine.
Some municipalities have “rainfall rules,” which automatically cancel the swim if rainfall exceeds a certain amount within 24 hours. That’s because heavy rainfall washes both contaminants (think sewage, fertilizer, pesticides, and animal waste) and debris (like branches and trash) straight into waterways, and neither issue can be quickly or easily fixed. Understanding the level of regulatory oversight can help you set expectations – races in heavily regulated urban areas are more likely to face last-minute swim cancellations than those in more remote venues.
Bottom line
No swim is ever “guaranteed.” Weather, water quality, and safety considerations always come first—and they should. But if you want to improve your odds of actually completing all three legs, take a little extra time before registering. Research the venue’s history, water quality, and seasonal risks. Look at geography: sheltered vs. exposed, clean vs. urban. Consider the size of the race and its resources.
Choosing wisely won’t eliminate every risk, but it can save you the disappointment of training for months only to end up running past the swim start in your bike shoes. After all, triathlon is meant to be swim-bike-run—and the best way to get there is by starting with a smart choice of race.
