How to Train for Your First 5km Swim

There’s something beautifully mad about deciding to swim 5km in open water. It’s not just a distance, it’s a calling. A conversation between you and the wild. When we set out to cross the Saltstraumen or swim the River Eden, we didn’t do it for medals or likes. We did it because the water pulled at something deep inside us, something old and elemental.

Training for your first 5km outdoor swim isn’t just about preparing the body. It’s about softening the edges of your fear and sharpening your sense of wonder. It’s about letting go of control and learning to move with the water, not against it.

Here’s how I’d do it. Not from a spreadsheet or stopwatch, but from the heart of the river.

1. Swim Wild, Swim Often

Pools are fine for technique, but wild water is your real training partner. Start by finding your local body of water, a lake, a river bend, a tidal bay, and get to know it like a friend. What’s the temperature like at dawn? How does the current behave after rain? Where do the birds sit, the wind bite, the weeds sway?

Begin with short, exploratory swims. 500m. 1km. 1.5km. Build slowly. Let your body adapt to the cold and the current, but more importantly, let your mind adjust to being out there suspended in a vast, moving element. I always called my local Lido, Brockwell Lido, the home ground. I treated it as a sports player would treat playing at home, it always gave my training an edge. Big Brother Robbie did the same thing when training to swim the 14km of Lake Ullswater, he treated the lake as his home venue.

“Don’t rush. The wild teaches patience, and 5km will demand all of it.”

2. Build the Engine, But Don’t Forget the Soul

Yes, swim drills matter. Yes, intervals help. But don’t fall into the trap of over-measuring something ancient and instinctual. Your 5km training should be part structure, part ritual. A few focused sessions in the pool each week (working on distance, endurance, and bilateral breathing), combined with at least one long outdoor swim to grow your grit.

Use those outdoor swims to stretch your limits. The goal isn’t just distance, it’s depth. Push your edge, not past it.

3. Get Cold, Get Comfortable

Cold water is the great equaliser. It doesn’t care about your VO2 max or how much Strava kudos you normally get. It humbles you in seconds, makes you raw and real. That’s why you need to train in it, regularly.

The trick isn’t just to survive the cold, but to learn its language. You’ll feel the initial sting fade into clarity. Your skin will burn, then buzz, then quiet. Each time, you’ll come out changed. Stronger. Sharper. A little more wild.

“We call it ‘becoming river-hardened’, your body remembers.”

4. Test the Kit, Then Forget It

If you’re swimming in a wetsuit, train in it. If you’re going skins, build cold exposure gradually. Either way, know your gear inside out. Goggles that fog? They’ll drive you mad at 3km. Chafing from a neck seam? That’ll become unbearable halfway through.

Train with the same gear you’ll race or adventure in. Test feeding systems if you’re using them. Try carb gels, jelly babies, or simply stop and float with a flask of warm Ribena strapped to your tow float. You’d be amazed at how many people turn up on race day and eat some gel they’ve never had before or drink loads of energy drinks they never train with. Don’t be the race day guzzler, your stomach will thank you for it. Stick to your tried and true (for me its Medjool dates stuffed with peanut butter).

5. Learn the Water’s Mood

5km outdoors is never just about the swim. It’s about the water’s character on that day, at that hour. It might be playful. It might be wrathful. Learn to read it like a sailor: watch for wind direction, entry/exit points, temperature shifts, weeds, wildlife.

Map your swim. Visualise it. Better still, scout it. Swim parts of it beforehand. You wouldn’t climb a mountain without walking the trail first. This isn’t absolutely necessary but it can give you an advantage especially if you are nervous.

6. Respect the Distance, Not the Clock

Forget time goals, your first 5km is about completion, not competition. Your aim is to finish strong, not fast. Swim like you're telling a story, not chasing one. Listen to your body. Keep your breathing steady. Let your stroke carry you, don’t fight it.

If you cramp, pause. If you panic, float. There’s no shame in slowing down. That’s the beauty of wild swimming it’s not a race. Bring that philosophy into the 5km, chances are you won’t remember your time but you will remember the experience and how you felt.

7. Swim With Someone (Even If You Finish Alone)

We brothers always swam together, not just for safety, but because shared suffering becomes shared joy. If you can, train with someone. Or at the very least, have someone on land keeping an eye on you. Wild swims are glorious, but they are not without risk.

Think about who you can share the experience with. Call that old friend you’ve not seen in a while, rope in that cousin who wants to get fit, go on that adventure you always wanted to with your mum. Your first km will be all the better and more memorable for having someone to share it with.

Final Words from the Water

When you stand on the shoreline, toes curled in the mud, nerves fluttering like birds in your chest, remember why you started. Not to tick off a bucket list. Not to prove anything. But because the water called you. Because something deep inside you remembered the wild.

Your first 5km swim won’t just change your fitness. It’ll change your relationship with the outdoors. You’ll know what it means to surrender and still move forward. You’ll learn that cold, darkness, distance, none of it is bigger than your will.

So take the plunge. Train with intention. Swim with heart.