Open Water Swim Safety

Original post 2012 - updated in 2018 and again in December 2020.

Over the last few years there have been a sudden increase in deaths during the swim leg of a triathlon. Being an active triathlete and someone who encourages people to participate in triathlons, this sudden increase in deaths bothers me. I collected a few articles and studies available online and contacted a few people who shared their thoughts and studies with me. (Thank you Brad Kearns, Race Director of the Auburn triathlon, for the prompt email and for being on the forefront of triathlon swim safety. Thank you Rudy Dressendorfer for the article and thoughts.)

I have summarized the notes below in points and added links to the full articles:

Preswim Safety:

Dan Empfield’s notes on a safe swim [Dan's article]:
1) If it is a warm day, do not suit up too early. This may cause you to heat up too much.
2) Get a properly fitted wetsuit.

3) Do some dry land and in water warm-up 5 to 10 mins before your start.
4) Line up at the start according to your ability.

Rudy Dressendorfer PT, PhD, FACSM – notes on a safe swim [Rudy's article]:
1) Avoid a tight wetsuit.
2) Do preliminary exercises before immersion to promote blood flow to extremities
3) Submerge gradually
4) Do an easy warm-up after immersion to help redistribute the central blood volume
5) Do not over hydrate within minutes before the swim start
6) In the event of a panic attack discontinue the competitive effort, float on your back and signal for help. Do not resume swimming until your breathing is back to normal.
7) If possible, become habituated to the swim venue in advance.

The common theme is:
A) WARM UP
B) PROPER WETSUIT FIT
C) DO NOT OVER HYDERATE
D) START SLOWLY
And I add, TRAIN WELL AND TRAIN FOR RACE CONDITIONS. A warm pool swim training plan will not help you for an Alcatraz swim. Train with a group - as race swims are a contact sport - with many people in the water. Train to get used to having contact and lots of turbulence in the water. 

Practice removing and putting your goggles on while in the water. Get comfortable doing that. Your goggles may leak, fog up or get knocked off during a swim. Train to be able to fix that during the swims.

One of the exercises we do with our new swimmers is; stopping them in the deep and making them all sing a song. It helps if you can be comfortable treading water (or just hanging in the deep if you have a wetsuit on) and not panicking. 
The Auburn Triathlon that used to be run by Brad Kearns, had initiated a mandatory warm-up prior to the swim start. Thanks to RDs like him we will see a good and safe change in triathlon swimming. 

Now days warming up is very common and even Ironman events have moved to a rolling or self-seeded starts rather than the old 2000+ people mass starts!

Further to the preswim safety notes/instructions, Rudy has written about the probable causes of pulmonary edema (PE) in healthy, experienced swimmers. Summary of his notes are [Full article here]:
1) Immersion in general – and face immersion in particular
2) Cold water
3) A tight wetsuit
4) Physical exertion without warming up
5) Excessive hydration


Here is an article on safety in Open Water Swimming from the US Masters website - this has some great points for general Open Water swimming and worst case scenarios:


Other articles and studies on Triathlon related deaths in water are:
Washington Post article: I agree more with Rudy's probable causes than panic attacks occurring in regular healthy triathletes. I'd agree that panic attacks are common in novice swimmers going out for their first few races. I have no data to back this, it is just a 'regular open water swimmer' hunch.

A JAMA study on Triathlon deaths

A JAMA letter, 'Causes of sudden death during a triathlon'

USAT is conducting a full study on these swim related deaths and their findings are yet to be published.

The USAT study that came out in Oct 2012 was, essentially, inconclusive. Here is the article from Triathlete magazine.

Non-competitive Open Water swimming 

Update for non-competitive Open Water Swimming. This is essentially for all of us who just enjoy the open waters and swim throughout the year. Where I am (Northern California) the water temperature does dip into the low 50sF (10-11 C) during the period November to March. A lot of folks swim without wetsuits - just be aware that they are conditioned for it. Don't just follow them and dive it. Work your way into cold water. Acclimatize! Be regular - join a group and be patient with yourself.  

I personally switch between wearing a wetsuit and not wearing one based on how long I intend to stay in the water, who I am with and the swim plan for the day. If I am swimming with my Team of new swimmers, I always wear a wetsuit. That extra wetsuit buoyancy makes it easier to help someone else in the water. 

And finally, be wary of evangelists - those that insist on their way being the best way - They will say things like "Go without a wetsuit, so much better!" or in the case of running "Run barefoot, it is so much better!" - Always begin within your limitations and work on your conditioning. As you get better conditioned you can start experimenting cautiously. Find what is good for you and what you enjoy and just do it. If you like swimming in a wetsuit - stay with it. Absolutely nothing wrong with that. 

Points to note (I will continue to add to this list as I learn more):

1) Never swim alone (buddy up).

2) Check with local swim group(s) or lifeguards about conditions in new venues you go to.

3) Avoid baitball areas in the sea. You can notice these by the congregation of birds in one particular area. That is a sign of possible feeding going on underwater - this attracts a lot different sea-life. I got caught in one in Santa Cruz a few years ago and the Sea Lions were not pleased. We (I was helping someone swim around the wharf) were very lucky and nothing untoward happened. 

4) Wear a bright swim cap (Orange or Yellow) and if possible, strap on a swim buoy - that makes you more visible in open water.

5) Increase your swim time in cold water slowly over a few weeks. Start with a  15/20 mins immersion and then build up over the next few weeks. Check for clawing of your fingers, slurred speech or mild disorientation. Those are early warning signs of hypothermia and you should start heading out of the water. 
As an example, I normally recite a favourite poem or sing a song after about 30 mins in - if I remember the words/lyrics I'm still good to go - if I struggle - it is time to hit the beach. 
(Of course, I do this in my mind...I don't just stop mid swim and start screaming; 
"All in a hot and copper sky, 
The bloody sun, at noon, 
Right up above the mast did stand, 
No bigger than the moon..." 
I'm not crazy! Or am I?)  

6) After exiting cold water, dry yourself off, dress warm and wait for about 20 minutes before you drive. Your body continues to cool post swim (called 'afterdrop'), so wait till you are warm and comfortable - then drive. DO NOT RUSH. 

7) Do not swim during a thunderstorm. (Don't run, bike or hike either. Stay indoors.)

8) Avoid open water for about 48 hours after a heavy rain. The storm drainage can increase the level of bad bacteria in the water. 

9) Check tides prior to swimming - specially in areas like the San Francisco Bay where the flood and ebb tides are really swift and cause eddies and reverse movements along the coast. Generally the best times to swim are the two hours bracketing High Tide (HT) and Low Tide (LT). Example - if HT or LT is at 10:00AM - it will be good to swim between 9:00AM and 11:00AM - it is slack period (Slack tide) and the waters are a bit calmer and stiller...generally. Tide Chart for Bay Area. Check water quality prior to swimming. Most beaches and lakes that are open for recreational swimming are tested regularly. Water Quality site in the Bay Area.

10) Maintain a modicum of fear and big dollop of respect for water. Do not be over-confident in your abilities. Know who you are going with for a swim, know their abilities. Do not overextend yourself. Know your own limitations. Keep it safe and fun.

Here is a great article from the Outdoor Swimming Society that covers some salient points on cold water swimming.  Enjoy!     

Back to the Gull Park, Foster City, CA Swim Post.

Some of the links I used in 2012 were no longer active so I have updated this post.
This blog post was updated on May 30, 2018. Further update on December 7, 2020 & April 2021.