Magical Night Swimming in Oban: Wild Swimming with Bioluminescence on Scotland’s West Coast

I’ve driven from the Cairngorms to Oban many times in recent years, but this time, the trip was a little different.

After a false start for our night swim adventure—when stormy weather and rough sea states cancelled our first attempt—we set off again with a positive forecast, clear skies, and rather a lot of excitement.

A West Coast Welcome

As soon as we hit the west coast and reached the first sea lochs near Fort William, we knew we were in for something special. The water was like glass—a perfect mirror reflecting the hills, with only the faintest shimmer.

As the light faded, the scene grew more magical. Sunbeams cut across the lochs like beacons, and Castle Stalker looked as if it had been painted onto the sky. Its reflection was sharper than the stone itself. By the time we rolled into Oban, the harbour had turned peach and red, the sun dipping low with not a breath of wind—and, mercifully, no midges.

Car Park Faff & Casting Off

We all met up in the car park before the swim. Most of the group knew each other already, but having travelled separately, it felt like a reunion of sorts, with lots of laughs and excitement. Meeting at 7pm before boarding a boat into the darkness was a little surreal, but I couldn’t have asked for a better group of adventure-hungry swimmy friends!

After the inevitable car park faff, we walked the ramp to the pontoons and boarded the familiar Basking Shark Scotland boat, with Shane as our captain and Evan as our wildlife guide.

We first headed towards Kerrera, home of the famous Craggy Island Triathlon, with the spectacular Gylen Castle looming over the bay. A ruined tower house at the south end of the island, Gylen sits dramatically on a promontory overlooking the Firth of Lorne. I’d swum there before in daylight—sun beams glittering through kelp beneath me, castle above me, a scene so mind-blowing it’s still etched in my memory. But this time, the wind and swell made it too exposed, so we turned back to find a calmer spot.

Gallanach Bay & a Bit of History

We settled on Gallanach Bay, a sheltered pocket of the mainland. Evan pointed out the crumbling building on the shore—it was once the western terminal of TAT-1, the very first transatlantic telephone cable system. Opened in 1956, it connected Oban with Clarenville in Newfoundland, enabling the first simultaneous voice calls across the Atlantic. A little slice of technological history, hidden in the quiet bay where we’d swim.

The boat slowed, sheep bleated invisibly on the hillsides, and we wriggled into wetsuits as Shane and Evan rigged up the lights. When the switch flicked, a green glow poured beneath the boat, lighting up sand and water. The darkness suddenly felt far less intimidating—almost welcoming.

Into the Water

The water was a balmy 15 degrees C compared to the Cairngorms’ 10 degrees C, though I still opted for a wetsuit (with the option of ditching it later).

With torches strapped to floats, we struck out in a triangular loop—towards shore, along the shallows, then back to the glow of the boat. The night swimming experience was magical: glowing floats of different colours bobbing like lanterns, stars glittering above, fish and crabs darting below.

At one point, Phil earned the nickname the moth, endlessly swimming towards any light source—floats, torches, even other swimmers. Cue a lot of chuckles as he bumped into people mid-stroke.

We paused for “star floats,” lying on our backs staring up at the Milky Way, satellites, and even a few shooting stars. The constellations were vivid—the Plough brighter than I’ve ever seen before.

Bioluminescence: Swimming Through Galaxies

Then came the real highlight. With the floats switched off and eyes adjusted to the dark, bioluminescence sparked to life.

This was my third time seeing it, but it never gets old. Tiny white sparks of light burst around us, like swimming through galaxies beneath the stars. Every stroke agitated the water into glowing fireworks.

Some of us sculled gently, others whisked or waved our hands vigorously underwater, and even those still on the boat could see sparks flying off our hands and feet. I developed a funny little whisking motion (or, as my little one would say, wind the bobbin up), while my brother perfected his karate-chop style. Whatever the stroke, it worked—the darker the water, the brighter the sparks.

What is Bioluminescence?

As my friend, ethnobotanist Susanne Masters, explains:

“Bioluminescence is the biochemical emission of light by organisms that might live along the shoreline or in the sea. Concentrations of creatures such as dinoflagellates—microscopic algae—can result in an otherworldly, sparkly swim. They capture energy from the sun and store it as luciferin, a light-bearing protein. When disturbed at night, they trigger a chemical reaction that breaks down luciferin and releases light—thought to be a defence against predators. In summer, calm seas and warmth help them aggregate. On a night swim, as your body moves through the water, little sparks appear. A duck dive down is like jumping into the Milky Way.”

If you want to learn more, Susanne and I created Wild Waters: A Wildlife and Water Lover’s Companion to the Aquatic World. It dives deeper into wonders like this. Here is one of my illustrations from the book!

Coming Back to Shore

Eventually, the cold crept in and we swam back towards the boat. I stripped off my wetsuit in the water—a much easier choice than wrestling it off on deck. (Note to self: next time bring a head torch. A float light works, but rummaging for dry socks by glow-stick isn’t ideal.)

Back onboard, we passed around chocolate, peanut butter–stuffed dates, and Percy Pigs. The boat hummed quietly across flat water, everyone sunk in that shared silence that comes only after something extraordinary.

Reflections

It’s hard to put into words just how perfect the night was. Clear skies, no wind, glowing water, a bunch of like-minded adventurers, and stars above us—it felt impossible to recreate. But even if it had been cloudy, even without the Milky Way, the magic of wild swimming and open water swimming at night would have been enough.

This swim really transformed my relationship with swimming in the dark. Up until now, my most vivid memories of night swimming have been tied to long-distance marathon swims—either setting off at 3am into pitch darkness for my English Channel solo, swimming right through the night on Loch Lomond, or starting and finishing in the dark on Loch Awe. Some of those experiences were good, others absolutely terrifying, but all of them were framed as part of a much bigger challenge. This time was different. To simply slip into the water at night, with the floodlights glowing around the boat and the incredible stars scattered across the sky, felt utterly transformational. I think I’m actually going to enjoy my next long-distance night swims!

Huge thanks to Shane and Evan, and to Lynda—my adventure planning partner in crime. We’ve talked about doing this for ages, and finally, it happened. Next year, we’re hoping to make night swims part of our bigger West Coast Adventure swim holiday. And if this was just the beginning… I honestly can’t wait.

Practical Kit List for a Night Swim

• Goggle or snorkel mask – to see the incredible underwater world and search for bioluminescence!

• Wetsuit (or skins if you’re hardy!) – you can even hire 7mm snorkelling wetsuits from Basking Shark Scotland if you are worried about the cold and want to stay in for longer.

• Extra neoprene accessories – hat, gloves, socks, vest – whatever extra bits and pieces you want to keep you toasty warm in the water.

• Tow float with light – visibility is essential. A bike light inside a tow-float works well, or attach waterproof LED lights to the outside of the float.

• Head torch – especially useful for pre- and post-swim faff on the boat.

• Torch/underwater light – optional – for spotting fish, crabs, and sparks below (these can also be hired from Basking Shark Scotland).

• Warm layers for afterwards – e.g. a warm changing robe, woolly hat and gloves.

• Snacks & hot drink – chocolate, dates, Percy Pigs… whatever fuels you best.

✨ Want to join us next time?

This was a recce trip for our 2026 West Coast Adventures.

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