On 24 August 1875, Captain Matthew Webb became the first person to swim the Channel, slathered in animal fat to fend off the cold. At the time, it was heralded as a feat of near-superhuman endurance. One hundred and fifty years later, I signed up for a modern take on the 33.3km (21-mile) swim (the shortest distance across the Channel, although Webb was blown off course and ended up swimming something like 63km). This Croatian adaptation involves swimming between islands off the Dalmatian coast, is split across four days and includes a welcoming hotel (the three-star Places Hvar by Valamar) to recuperate in at the end of each day. And thankfully, neoprene has replaced tallow.

The trip is run by UltraSwim 33.3, a new company named after the Channel stretch, offering multiday swim challenges in spectacular locations – Croatia, Montenegro, Greece and Switzerland – with an emphasis on comfort and support.

“The Channel is the Everest of swims,” says Mark Turner, UltraSwim 33.3’s co-founder. “But the window to do it is short, it’s expensive, and – let’s be honest – not a particularly appetising stretch of water. With us, you get the same distance in beautiful surroundings, without having to rough it.”

I’ve been on swimming holidays before with companies such as SwimTrek and Strel Swimming Adventures, and I’ve swum up to 5km a day, but with breaks for drinks, lunch and soaking up the sun. UltraSwim takes a more structured, challenge-oriented approach. Each day begins early – we are in the water by 8am, before boat traffic picks up – and swimmers go up to 12km without pausing for more than a quick pit stop.

A detailed training plan landed in my inbox after I’d signed up and I quickly realised I wasn’t fit enough, or perhaps was mentally unprepared, for the full 33.3km swim. Thankfully, there were two shorter options available: the 11.1km “Discovery” and the 22.2km “Build” packages, both nodding to the Channel challenge.

On the first day, we set off from a jetty close to the hotel and, within minutes, I spot an octopus waving lazily from its underwater garden. I’d love to linger, but time and tide wait for no swimmer. Several kilometres later, I stumble out of the water on to the beach at Uvala Veli Dolac, exhausted but elated. We are greeted by a spread of high-energy snacks and a lot of talk about carb loading – a far cry from Webb’s fuelling strategy of beer, brandy and beef tea.

According to the Channel Swimming and Piloting Federation, Webb’s swim has now been repeated 3,250 times. The endurance trend is visible in other areas, too, from ultramarathons and multiday cycling tours to open-water relays. Increasingly, it seems, people want to return from holiday not rested but with a sense of accomplishment.

On days two and three, we tackle some proper “Channel” swims across 2-3km stretches of open water, from the Kabal headland to Stiniva beach, and Cape Pelegrin to Palmižana. On the map these are marked as ferry routes, but the views I enjoyed from the deck when I arrived in Hvar – all pine-studded islands and turquoise waters – feel very different when in the water: a distant headland to aim for, choppy seas and the occasional jellyfish.

I’ve never attempted anything quite like this before, and it’s not a challenge I relish. But I put my head down and try not to think about how far I am from dry land. There’s a GPS tracker in my tow float, kayakers on either side, and a clear course to follow – thankfully more straightforward than the one Webb swam, where strong tides dragged him way off course, turning a 21-mile crossing into a 39-mile slog.

As I swim for just over two hours, I find it hard to fathom how he kept going for nearly 22. I distract myself by recalling snapshots from the trip: the 16th-century Tvrdalj Castle in Stari Grad, where the poet Petar Hektorović once lived; and the Diocletian’s Palace in Split, where I spent a relaxed day exploring its golden alleyways and multiple layers of history, from the Roman and Venetian empires to Yugoslavia and the past 30 years of an independent Croatia.

Once we complete the open-water channels, we circle back into gentler waters around the Pakleni archipelago, covered with the pine, wild rosemary and lavender that flavours the local honey. The name “Pakleni” comes from paklina, a pine resin once used for boat building.

Our 160-strong group is made up of swimmers from across the globe, from as far and wide as Brazil, Dubai and Australia. There are almost equal numbers of men and women, with ages ranging from 20 to 73. Some are training for an actual Channel crossing, others just want a challenge.

“It’s type-two fun,” Joe from Dublin tells me. “The kind that’s only fun after it’s over.” I think I’m more of a type-one (enjoying things at the time) person, but I do enjoy swimming across the sun-dappled kelp forests, the calm rhythm of stroke after stroke, and the quiet pride of finishing each day’s swim.

“We find that people surprise themselves,” says Turner. “The way we structure it with pacing and support, swimmers who’ve never gone beyond a few kilometres leave feeling they’ve done something extraordinary.”

Non-swimming partners aren’t left out. They can follow by boat, cheer from the shore or explore Stari Grad and Hvar. One non-swimmer told me he’d racked up a fair few kilometres on an ebike, visiting lavender farms, vineyards and sleepy fishing villages. “Other than a brief dip, swimming’s not really my thing,” he shrugged. “But my girlfriend loves it, so we’re both happy.”

On the final day, we aim for the bell tower of St Stephen’s Cathedral and swim the last few kilometres into Hvar’s harbour, emerging beside the Venetian arsenal to a glass of champagne, handed to us after we pass the finishing posts, to bemused stares from regular tourists.

A few hours later, after a soothing massage in a spa hotel, I’m wandering Hvar’s labyrinthine streets, stopping to enjoy fresh fish and Croatian wine, with no more talk of carb loading. I didn’t win anything. I didn’t swim the full 33.3km. But I completed the 11.1km course and tasted something akin to what Captain Webb must have felt: the slow, steady triumph of body over distance, albeit without the freezing water of the Channel, or the beef tea. And, instead of the pale grey cliffs of Cap Gris-Nez to signal the end, the golden limestone of Hvar.

The trip was provided by UltraSwim 33.3. Packages from €1,800pp for four nights (in a group of four, the fourth swimmer goes half-price), including hotel accommodation, breakfasts, post-swim lunches and guided swims. The next Croatia dates are in 2026 but places are available this year on trips to Montenegro, Greece and Switzerland