This weekend saw the 31st World Bog Snorkeling Championships, both for swimmers and for underwater bicyclists.
While most people were out enjoying their long weekend and trying to catch the fleeting sun, a group of cycling enthusiasts were racing through a boggy trench in Powys, Wales.
They were competing in the World Mountain Bike Bog Snorkelling Championships in Llanwrtyd Wells, where competitors have to ride a mountain bike as fast as they can along the bottom of Waen Rhydd bog – a two-metre-deep water-filled trench.
The bikes are specially prepared with a lead filled frame and riders wear lead weight belts to avoid floating off the bikes.
The tyres are filled with water to ensure grip on the bottom of the trench, and divers are on hand for safety purposes.
Oliver McKenna, a 36-year-old mountain biker from Brighton, was crowned champion in a close-run contest in which he trailed behind David Williams in the opening run, but claimed victory with a time of 1 minute 04.94 seconds in his second attempt.
The competition, which took place on Saturday, is run alongside the World Bog Snorkelling Championships, where swimmers have to complete two laps of a 55 metre (180ft) long bog.
And for those who can't decide between bog snorkelling and biking, there is even a bog snorkelling triathlon.
There's more at the link, and at this picture gallery.
Here are the swimmers at work:
And here are the mountain bikers:
Sooner them than me!