In summer, northern Europeans are prone to go a little bit crazy. It’s probably the long winter that does it: the endless nights; the short, twi-lit days. Huddled indoors, they have plenty of time to think about all the stuff they’ll get to as soon as their part of the Earth tilts back toward the sun.

When, at last, their surroundings are transformed by golden warmth, there is only a limited window of opportunity in which to put their pent-up schemes into action.

Would it, for instance, be possible to drive a snowmobile across an unfrozen lake? Come the first flush of summer, they try it. It turns out it is possible, with sufficient run-up and enough speed (though nobody has tallied how many rusting snowmobiles lie at the bottom of Icelandic lakes from the early attempts).

Can you play soccer in a peat bog? Every June, there is a championship held in Finland proving that you can, though not easily. Or cleanly. You’ll never see a laundry detergent commercial offering to get the stains out of uniforms after a swamp soccer match.

It was within this northern tradition of nutty pipedreams that, in 1996, an Estonian, Ado Kosk, conceived a new sport. Or rather, he revived and formalized an old one, for it seems that Estonians have been kiiking for centuries.

The Estonian language is impenetrable at the best of times. To outsiders, kiiking could refer to … well, just about anything. With a little folkloric research, you will discover that a kiik is a traditional wooden swing. What sets an Estonian swing apart from the childhood swings we’re familiar with is that it dangles from rigid arms, usually made from wood.

But how does a humble swing become the basis for a mad northern European sport?

Kosk’s brainwave was to realize that if the swing’s frame was substantially heightened, and if the wooden arms were replaced with steel, then in theory it would be possible to swing 360 degrees: You would be able to swing right over the top and come back down the other side.

Theory was put into practice in the village of Viimsi, on the shore of the Baltic Sea northeast of Estonia’s capital, Tallinn. The pioneers honed the equipment and devised the techniques necessary to generate sufficient momentum.

The kiiker stands with feet securely strapped to the swing and sweeps back and forth like a metronome, using the entire body to maintain the rhythm, squatting like a skier on the back swing and straightening up on the follow-through.

The swing rises a little higher each time until it is almost vertical above the frame. At this point, the kiiker reaches heights of 30 or 40 feet, depending on the length of the swing’s arms.

The tension builds. A couple of times the swing is momentarily stationary above the frame, with the kiiker perilously upside down. Then gravity pulls it back the way it came. With one final, muscle-sapping effort, the 360-degree swing is completed — as satisfying as hitting a home run or throwing a touchdown pass.

From parochial beginnings, this addictive pastime has spread beyond the Baltic. Kiiking frames are increasingly springing up in the United States; a new summer sport is taking hold.

Back in northern Europe, everything is currently in the cold grip of winter. Frustrated sportspeople endure the long nights, dreaming of summer and the new ideas they will be able to try out. In some remote homestead in Scandinavia or the Baltic States, the next big sporting craze could be in someone’s head right now.