Updated September 25, 2025 09:15AM
Do Triathletes Really Need to Worry About Sharks in Kona?
With various reports over the years of “large marine life,” writer Tim Heming asks experts to set the record straight on the risks of sharks in triathlon (and at the Ironman World Championship).
Should triathletes participating in ocean swims be worried about sharks? Triathlete contributor Tim Heming speaks with experts. (Photo: Ironman)
“You’ll never go in the water again,” was the tagline for the 1975 movie Jaws, and as the film celebrates its half-century anniversary in 2025, for many people who watched it, sadly, that was probably true.
Thankfully, triathletes either seem less affected by Steven Spielberg’s psychological thriller or figure expensive neoprene is less appetizing than the flesh of beach-goers at the imperiled (and fictional) Amity Island.
Thankfully, shark attacks in triathlon races are rare to the point of being non-existent. But is that threat changing with the climate, and if it’s not sharks, is there other marine life lurking beneath that we should be worried about?
With the most famous race in the sport, the Ironman World Championships on the Pacific island of Hawaii, on the near horizon, let’s start there.
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Are there sharks at the Ironman World Championships in Hawaii?
It’s easy to fearmonger, but the presence of sharks around the tropical archipelago has long been an emotive issue. Spooked by the perceived threat of the tiger shark, which can grow up to 15 feet long, a controversial 17-year culling program existed until the mid-seventies, reducing numbers by more than 4,500.
“Shark hotspot” Google searches typically list Hawaii alongside locations such as Australia, Bahamas, Guadeloupe, Reunion Island in the Indian Ocean, South Africa, and the “shark bite capital of the world,” New Smyrna Beach in Florida.
But in terms of the chances of an unfortunate encounter, it’s extremely rare. The popular beaches of Maui and Oahu – both on different islands than the spiritual home of triathlon – are where most attacks are reported, but it’s also a function of more people in the water.
Dr. Kim Holland of Shark Research Lab at the Oahu-based Hawaiʻi Institute of Marine Biology (HIMB) says only three to four attacks occur per year in Hawaii, most being non-fatal – compared to an annual average of 40 drownings. Given there are thousands of swimmers, surfers, and divers in the water everyday around the Hawaiian islands, it puts the odds of an attack at quite literally millions to one.
The Shark Research Lab uses satellite-linked transmitters to track shark movements, and Holland holds few fears for the Ironman, “I see no reason why participants would be exposed to any greater risk of interaction with sharks than any other ocean user,” he says. “Harmful interactions with sharks in Hawaii are very rare, and I see no reason why Ironman activities would change this.
“If there were extenuating circumstances at the time – for instance, a whale carcass in the vicinity – I am sure the ocean safety professionals would be aware of this and proceed accordingly.”
Asked whether changing ocean temperatures might alter shark movements and make them more of a threat, he adds: “There is currently no indication of any changes in shark behavior or distribution in Hawaiian waters due to global changes in ocean conditions.”
The Shark Research Lab is also investigating the effectiveness of possible shark deterrents, although, according to an eyewitness at last year’s Ironman event, they might have Mother Nature providing some support in that respect.
Michael Arguello, a resident of the islands, took a number of pictures that showed large marine life in Kahului Bay, which is to the south of the swim start in Kailua Bay, and near the turnaround point of the 2.4-mile first discipline.
Arguello added the following commentary: “Well that was an exciting swim event for Ironman. Shark rolled in at Kahului Bay and multiple pods of bottlenose and spinner dolphins swam up between the swimmers and the shark, shielding the swimmers.”
“A line of dolphins protected the swimmers and a separate group kept the shark stuck near the rocky coastline. This water zone is a federal dolphin sanctuary and this is very much their territory – it was interesting the dolphins protected the swimmers the way they did and even involved mixed species of dolphins (bottlenose and spinner dolphins are very different).”
Although there have been anecdotal accounts of this sort of behavior, before we stake too much faith in the lifeguarding qualities of dolphins, Dr. Holland isn’t convinced, feeling that the co-occurrence of the dolphins and shark was likely “more coincidental than intentional.”
What does Ironman say about sharks?
Clearly, a shark attack during the swim would be very bad news, not just for the individual involved, but for the Ironman brand as a whole. For most rational individuals, swimming, biking, and running 140.6 miles is probably enough of a deterrent as it is.
With this in mind, Ironman swim courses are carefully chosen in areas with very low shark risk, but where there is an increased chance of sharks, such as Western Australia (Busselton), Ironman says it puts a robust management plan in place.
For example, the swim course in Busselton is designed to run within 300m of shore and take place over two laps.
It allows for greater coverage of water safety assets, less exposure to the weather, making for better swim conditions and – in the event of a mass swim evacuation or individual water-related incident – athletes can make it to shore quickly.
It is also designed in consultation with local shark monitoring authorities and community experts, says Ironman – including use of the Department of Fisheries Shark Monitoring Beacon in multiple locations along the Busselton Jetty and regular monitoring of the SharkSmart website, provided by the West Australia Government.
In addition, Ironman says it employs a private helicopter and shark spotter to assist in monitoring the swim course on race day, operational 30 minutes prior to swim start and for the duration of the event. Volunteer marine rescue also provides vessels that monitor the perimeter of the swim course
There are different action points depending on how close a shark is sighted to the course, Ironman adds. For example, if it is less than 1 kilometer away and headed toward the course and is deemed a threat, the swim will be suspended or evacuated.
If it’s further afield, different levels of surveillance are deployed.
Finally, Ironman notes that if the swim was to be canceled due to the presence of a shark, contingency plans are put into action to allow the event to continue as a bike-run.
With vigilance high, it’s hard to find incidents at any official events, whether Ironman branded or not.
How can shark attacks be prevented in triathlon and open-water events?
Precautionary measures are regularly front of mind. For example, Hawaiian channel swimmers, such as those attempting the 26-mile Molokai to Oahu route, are often accompanied by kayaks equipped with shark shields that emit an electric field that causes any approaching sharks enough discomfort to turn away.
At other locations, like the Midmar Mile open-water swim near Durban in South Africa – nominally the world’s largest participation open-water swim with more than 15,000 entrants – sees organizers deploy nets, patrol boats, and shark spotters for safety. And other popular mass-participation swims like the Bondi to Bronte and Cole Classic in Australia have sometimes seen shark-related course adjustments or temporary delays when spotters raise the alarm.
Eric Gilsenan has been a race organizer, lifeguard, and water safety official at various triathlons over the decades, including the Escape from Alcatraz Triathlon, located in the notorious shark breeding grounds of the San Francisco Bay. Gilsenan says triathletes’ concerns should be focused elsewhere.
“Certainly, having done the Escape from Alcatraz from 1989 to 2022, I never personally saw a shark,” he says. “I’ve seen dolphins and sea lions in the bay, but I’ve never seen sharks. Triathletes have a tendency to overthink things. Imagine that! Unfortunately, you’re much more likely to get hit on your bike by a car compared to being bit by a shark. Race week in Kona, with all the activity in the bay, the sharks aren’t entertaining dining in that region. They’re out deep or down the Kailua coast.
“I’m not saying it’s never going to happen because it has, but the likelihood is not worth the fear. Pulling a hamstring or crashing on the bike is more likely to be an injury than a shark attack in triathlon. So sleep well, get a massage, always thank the volunteers, and aloha, see you in Kona.”
Shark attacks in the open water
There have been triathletes who have been less fortunate in training, such as Maria Korcsmaros, who returned to the sport after a near-fatal shark attack. Korcsmaros joined the “bite club” at Newport Beach, California, in 2016, courtesy of a 10-foot great white. “I chose to become an advocate for sharks because I wanted people to understand that it really is a rare occurrence,” she said, also noting the motivation to get back in quickly because of an upcoming race she’d already paid for.
What other sea life should we be concerned about?
Jellyfish are the obvious ones, if the recent Ironman World Championship is any guide: It almost became a running joke (if a painful one) at last year’s race in Kona as the pros lined up and were consistently stung as they waited for the cannon.
After asking the photographers at the start whether they had any vinegar, eventual winner Patrick Lange (GER) was seen icing his stings in the post-race press conference, saying: “I’m still in pain. I have it on both of my arms and my face and my feet, and it’s really hurting.”
That Lange fought back to win a third title and set a new course record, matched the memorable feat of Switzerland’s Daniela Ryf, stung under both armpits six years earlier. “I was so happy I didn’t give up,” she said. “I knew there were going to be little kids watching that race and as a champion, I think you should try – whenever possible – not to give up.” She won in a blazing time of 8:26:18, which shattered the previous course record by approximately 20 minutes.
While jellyfish blooms can be pointed out if spotted, it’s not always immediately apparent, and athletes do react differently. Australian Matt Burton was forced to quit last year’s race when he suffered an anaphylactic response, later explaining that he has a history of hypersensitivity to stings.
There are a few other notorious culprits in triathlon, notably stingrays and sea urchins, who don’t like being stomped on during beach starts – as pros Chase McQueen (USA) and Dan Dixon (GBR) can attest, when racing a Triathlon Cup event in La Paz, Mexico in 2023. McQueen finished on the podium; Dixon didn’t finish at all. Both ended up with medical treatment, the venomous spines causing pain and inflammation.
But for the most part, have a healthy respect for marine life, take precautions where necessary, and enjoy your sport. As a friend replied when asked whether there are likely to be sharks in the ocean. “Probably. After all, it is where they live.”
If you are still concerned about marine life, here are a few safety tips
- Swim within marked courses and avoid venturing into rocky or heavily vegetated areas
- Shuffle your feet in shallow water to avoid stingrays or sea urchins
- Use rash guards or wetsuits to reduce jellyfish and coral exposure
- Keep an eye on local advisories – lifeguards or race organizers often report jellyfish blooms or unusual animal activity
