Cold Water Swimming

Cold water swimming is not something one should jump into lightly. Acclimatization to cold water is the biggest secret I can share. Spending time in progressively colder water goes a long way to preparing for a Puget Sound swim. Also never attempt to swim alone, especially in cold water. Even having someone on the beach while you swim to call 911 in case of a water emergency may just save your life. Always wearing your swim safer buoy will make you easier to spot in the water. There are some relaxed escorted swims locally you can also benefit from tips from the organizer and other experienced swimmers.

There are many online guides and books available providing advice and tips on both open water and cold water swimming. A great source of cole-water training can be found at Santa Barbara Channel Swimming Association everyone can acclimate to cold water to some degree. It takes the discipline of actually getting into cold water over a series of swims. The unpleasant part of acclimation is that you actually have to continue to get into water that is below your “comfortable temperature.” Cold water baths and showers help some people. A lot of cold water acclimation is mental. Training your mind not to respond to the cold is part of the process. Talk yourself through it. Convince yourself it’s not all that bad. “I can take 10/100/etc. more strokes.” This actually works.

Swim Defiance will occur in Commencement Bay across Dalco Passage. The water temperature usually stays between 54 - 59º F year around. For comparison, the pool water for swim meets at the King County Aquatic Center is usually kept around 77-78º F. Other than cold water, the trip across Dalco Passage will require you be cognizant of currents. However, the swim is strategically timed to coincide with the least amount of current at 35 minutes before the peak of low tide at 09:06 AM. This page will provide you with some Cold Water Swimming and Navigation TIPS for a successful swim.


One good thing about acclimation described above is that it stays with you. Once you've acclimated, you develop a durability and permanence, resulting in the fact that you never really go back to the point where you can't handle cold anymore. From year to year when you are actively acclimating, you often take 2 steps forward by the end of the season and only a 1/2 step backwards at the beginning of the next. Be aware that there are some people who, due to their own body chemistry, are unable to acclimatize to racing longer than a mile in water under 65 degrees, be sure to know if that is you before attempting longer distances.

No cold water information is complete without a discussion of hypothermia. The normal body temperature is 98.6º F (37ºC). Hypothermia develops when the body temperature falls below about 95ºF (35ºC). Moderate hypothermia can usually be reversed, and a complete recovery made if it is recognized and treated quickly. For the quickest relief, combine drinking warm liquids with taking a warm shower, removing your wet bathing suit, and donning dry clothing, sitting in a warm environment (a.k.a. a warming tent). In most cases, drinking warm liquids appears to expedite recovery. To help avoid this heat deficit in the first place, I can’t stress enough the importance of EATING before cold water swimming. A meal of slow burning fuel like oatmeal w/fruit or pancakes with nuts is an example.

If your body temperature falls much lower than 95ºF (35ºC) and you exhibit two or more of the symptoms of hypothermia as listed, YOU WILL BE PULLED- PLEASE don’t fight us on this---it is for your own good! We have a well-organized and USMS approved rescue plan organized for this instance. The weather conditions of the day will also play a part in the onset of hypothermia. Obviously, warm sunny skies will keep a swimmer warmer than a cold, overcast/drizzling day.

Symptoms of hypothermia:

  1. Uncontrollable shivering
  2. Disorientation
  3. Irrational behavior (The supporter says go left and the swimmer goes right)
  4. Blue lips (very obvious)
  5. Inability to concentrate or respond to simple requests or questions (“What day is it today?)
  6. Slurred or uncoordinated speech
  7. Ashen or gray skin color
  8. Lucidity tests (“What town do you live in?” “How many fingers am I holding up?”, etc.)

Cold shock response is an entirely different thing to hypothermia, it’s the body’s response to sudden cold, with gasping reflex, hyperventilation and possible acute pain in hands, feet, face and head, and even cardiac events. The biggest danger in immersion is uncontrolled hyperventilation leading to sudden aspiration of water. If you gasp and breathe water into your lungs, you could drown. DON’T DO THIS!

I will be providing several kayak escorted swims along Ruston Way and at Owen Beach inside Pt. Defiance Park, 5 weeks before the event to help with interested participants' acclimatization. It is important that you have done some previous swimming training and that you have your wetsuit for this practice.  Please sign up for Swim Defiance before the practice swims to be sure you are covered by our secondary insurance. These times are posted on the website. As always, I am available for questions and extra swims if someone has a very challenging schedule and not able to make the ones posted. My phone number is 253-426-0588.




Cold water training for Swim Defiance is FREE for current BERN members and swimmers who have registered for Swim Defiance. Please contact Diana before coming to the training.

If you are planning to attend a swim, confirm with Diana; in person, by email, OR phone/text 253-426-0588 so we don't start the swim without you.

6 Practice swims for the 2023 season will start June 28th and conclude July 31st.


  • June 28 / Wednesday at Owen Beach in Pt. Defiance Park, 6:00 PM.
  • July 6 / Thursday at Owen Beach in Pt. Defiance Park, 6:30 PM.
  • July 11/ Tuesday at Owen Beach in Pt. Defiance Park, 6:30 PM.
  • July 19 / Wednesday at Owen Beach in Pt. Defiance Park, 6:00 PM.
  • July 25 / Tuesday at Owen Beach in Pt. Defiance Park, 6:30 PM.
  • July 31 / Monday at Owen Beach in Pt. Defiance Park, 6:00 PM.

We reserve the right to change course / location due to conflicting events, tide and snags that can alter the course / location.

Our practice swims offer an opportunity to swim with others, on a pre-approved safe course, at various Puget Sound beaches. Water temperature in the Puget Sound varies over the season from about 54℉ at the start of June up to a high of 59℉ near the end of August. Upwellings of colder water around the course can be refreshing on a hot day, but we do advise wearing a wetsuit both for warmth and floatation. 


  • 2 swim caps, 1 brightly colored swim cap (not white), 1 silicone or neoprene for underneath
  • Swimsuit and towel
  • Wetsuit, neoprene gloves/booties (not mandatory for practice swims but a really good idea).
  • Whistle (not mandatory but a really good idea)
  • An after swim snack or warm drink, rinsing water and change of clothing for post swim

You should be comfortable swimming 1200 yards (48 lengths in a 25 yd pool) / 1000 meters (40 lengths in a 25m pool) and have all the recommended safety items.


Change rooms, washrooms, no showers, concession stand, FREE parking lot. We do not always have a volunteer to watch your gear while you swim, so prepare to leave valuables in your vehicle or lock them with your bicycle on the beach. Diana will have a dry bag to hold car keys safe but there may be a lag to retrieve keys for faster swimmers as Diana will need to remain with the slowest swimmer thru the end of the swim.


Struggling with open water swimming or feeling out of your depth? Check out our Bernardo's All Stars program to get your skills and improve your open water confidence. Click here for more information. 


Swim safety buoys are MANDATORY for this race. We will some for sale at the event.  Below is just a sample not the actual ones for sale on race day.

Safer Swimmer Buoy is Mandatory for Swim Defiance sells Safer Swimmer Buoys. Check out our recommended items for Swim Defiance swimmers.

Buy your Safer Swimmer at Swim Outlet