I'm by no means an expert at cold water swimming, but after dozens of dips, I have found a number of hacks, tricks, and simply foundational musts that help my swims, go smoothly!
Also, before we go into the rest, it's always suggested to have a buddy or tell someone what you're doing (including where, when, how long, and what to do if they don't hear from you by a certain time.)
In terms of safety and health, cold can do some bigtime impacts on you, so please check with your healthcare provider and use your own judgment and discernment about whether you are healthy enough to engage in cold water, breath, and other intense activities such as this. These are tips that have worked for me, but I make no guarantees about anything and this is NOT MEDICAL ADVICE.
Check your weather.
Are there strong waves or wind? Will there be ice to break through? Ice shelf? Is there snow on the beach? If there's been a lot of rain or melted snow, is there sewage run off / overflow?
If the temps are below freezing, just know that getting out of the water will be extra brisk and will influence what you pack for warming up.
Know that the experience of a cold swim with sunshine and no wind will be dramatically different than one without. You don't have to let these feel like limits or predetermined experience (especially because the cold water is here to teach you MIND OVER MATTER). Knowing this can simply help you share with your mind that you are aware, you are safe, and you have all the materials you could need.
If it's really cold, packing is NOT light.
3-4 towels. I recommend a few towel/sheets, which I use our 100% cotton beach towels (like this COLD WATER SWIM CLUB one) for. You may want one for under your feet when changing (because you may want to drop your suit right at the beach). You may want one for your hair, if you choose to go under. It's good to have an extra just in case you drop one in water or sand.
Have a warm beverage waiting in your vehicle.
Pack or wear a hat. If you're not going under water, wear it in the water! If you don't want wet hair but want the benefits of underwater on the face, wear a swim cap!
If your circulation isn't excellent or you're not sure about the bottom that you'll be waking on, have water sandals or swim booties.
Have shoes, socks, and clothing that are loose enough to put on a slightly damp body. I wear wool socks and sandals. I designed this hoodie dress FOR swims.
Oversized winter jacket. They make jackets for this specifically. Options here and here.
Note: I change on the beach into warm clothes unless it's windy, in which case I run to the car.
Plan it out / train
Training before your swim is nice, but it's by no means mandatory. Wim Hof offers great training protocols.
Cold baths and showers. I don't like wasting cold water in a tub, so I take cold showers nearly daily (whether a blast or the entire duration. Saves lots of water not waiting for it to get warm). As I do these, I say out loud "warm" on repeat, which I also do when I'm entering the cold water in a lake or ocean, to start to confuse my body about temperature. The body starts to associate the sensations of cold with the mental understanding of warm, which starts to make the cold seem a bit friendlier.
Breath. Deeply. The slower you can breathe, the more you are essentially "tricking" your body into thinking that a stress response isn't necessary. Doing things that you wouldn't do while stressed (laughing, humming, breathing slowly, slow moments) will help reinforce that you're calm.
See yourself setting up, feeling warm, completing your swim
See yourself warm and smiling after your dip, being grateful for the infinite capacity of both mind and body.
Visualize your blood flowing calmly, healthily. Your body's tendency will be to have the blood from the extremities retreat to your core to preserve your organs, so affirm to your body that you are safe and in control.
Prep your body.
Don't dip on a full stomach. Eat light and save your next meal for after.
Try to increase your core temp before you get in the water. Breathing, engaging muscles (walking, jogging, jumping, or other types of workout), will help the cold feel a bit less shocking.
Breathe deeply and slowly. Box breathing (inhale, hold, exhale, hold for equal counts) can be very calming.
Listen to music that makes you feel calm, content, happy. You will feel LIT and energized after you exit the water, so use the time before the swim to try to bring yourself to a more neutral, calm, joyful state vs. super adrenalized.
Surrender to the experience
Prepare to end quickly if your body is struggling with it. If you go past the point of your body and mind now panicking and finding true stress, moving towards shaking and hypothermia, warm up!
Prepare to stay in longer if things feel nice. Don't tell yourself that you need to get out after a certain length if in the moment you are trusting that you feel great!
Smile, laugh, scream, whatever you feel, but also know that there is great power in remaining quiet, still, inward, and deep in meditative breathing.
The cold is a beautiful way to train your body that stress doesn't mean shutting down. YOU CAN DO HARD THINGS. You powerfully and intensely learn that your mind, body, and soul are an integrated team. Imagine if you carried that same energy into all areas of life when stress emerged? You just might be capable of everything you're dreaming of...