The sun reflects off the still surface of Harthill reservoir on a warm early summer evening.
It’s a picturesque and peaceful place, an ideal destination for a sedate stroll or a sit down on the grass bank.
On Tuesday night however, the calm was broken by dozens of hardy open water swimmers.
There may be a national decline in the number of people propelling themselves through a swimming pool for recreational purposes, but Yorkshire Outdoor Swimmers are experiencing a boom.
Saturday 6th June saw 120 enter the water they share with sailing enthusiasts and fishermen, despite 45mph winds.
Even the closure of the 750m ‘long course’ for safety reasons didn’t deter the hordes of swimmers, they simply ploughed through the waves on the 250m short course.
The following Tuesday night the hut that houses a bar, changing rooms and showers, is teeming with people signing up as new members.
Not long after 6pm, a steady stream of men and women, some in full wetsuits, some in minimal swimwear, are checking in with a club representative on the jetty before plunging headlong into 16°C water.
Regulars call this nice and warm.
Wendy Figures, one of the members tasked with swimming around the course alongside newcomers, doesn’t feel the need for a wetsuit.
She’s an open water champion, and has completed the legendary ‘ice mile’ – a one mile swim in water of 5°C or less.
The club is open all year round, and they’ve had to break the ice on occasions, to gain entry to the water. They’re a tough breed.
For first timers, however, the water is cold.
The shock, even when wearing a nice thick wetsuit, sends your breathing into an almost comical stuttered rhythm.
As buoyant as the wetsuit makes you, getting a smooth swimming stroke going is a tricky task when you can’t get full control of the air flow into and out of your lungs.
An attempt at front crawl is almost overwhelming, putting your face into murky water that lets you see very little other than the reservoir’s tallest weeds.
You tilt your head to breath and your vision is obscured by the sun’s glare dancing on water droplets on your goggless.
A ‘supported swim’ is just that, an expert or coach like Wendy by your side at all times, constantly checking on your state of mind.
Should anything untoward happen there’s a team of volunteers and a lifeboat on standby, along with a list of rules and regulations as long as your arm that must be read and signed before you leave dry land.
Yorkshire Outdoor Swimmers go to great lengths to ensure all eventualities are covered – it took them 18 months to get the necessary permissions and licenses in place before they launched in April 2014.
And when you realise that you’re going to be well looked after, the shock of the cold subsides and your breathing settles into a normal rhythm, open water swimming rewards you with an exhilarating experience.
There’s an undeniable buzz, cutting through the water, in acres of space, with the sun beaming down and the weeds tickling your hands.
Triathletes and Ironmen get their necessary training in at Harthill, but a huge number of the 600-plus members of Yorkshire Outdoor Swimmers are quite literally that - people who swim outside in lakes, reservoirs and the sea.
They’re addicted to their sport, or past-time, and they’re evangelistic. The talk in the changing rooms is almost exclusively positive about how beautiful it is in the water. Those who braved the waves in Saturday’s windy conditions talk of how ‘interesting’ and enjoyable it was.
New people are welcomed with open arms, and an Introduction to Open Water Swimming (ITOWS) course, which guides them through the basics; acclimatisation, floating, breathing, safety, sighting, so you don’t veer wildly off course, stroke development and getting out of a dripping wetsuit.
Membership costs just £10, and it’s £3 for each swim. Wetsuit hire is £5.50, swimming hats a couple of quid, but crucially the post-swim cakes baked by members are free. Most who indulge leave a donation.
It’s not just a place to go for a quick dip, they’ve built a community with trips away to major events like the Great North Swim, and a thriving Facebook group.
Over 1,000 have joined the Facebook page, and more than 300 follow YOS on twitter. Word is spreading.
And there’s more to come from this fledgling sporting organisation, who are dipping their toe in event management.
On Saturday 20th June open water coaching outfit Swim Your Swim and Chesterfield Triathlon Club will team up with YOS to host an Aquathon; a 750m swim followed by a 3km run.
That will presumably be followed by future events of the competitive kind.
For lovers of outdoor pursuits it’s a must-try experience.
It’s so much more engaging than a swim in a lane, in a heated pool.
There’s next to no chance of remembering your real life stress when floating in a lake of unknown depth, focusing on breathing, technique and direction.
Such an addictive sport will surely keep the YOS membership numbers on an upward curve as they move deeper into their second year of existence.
Come on in, the water’s ‘warm’.