Bohus Fortress provided a spectacular setting on Tuesday for the second stage of the O-Ringen PreO competition. In PreO, the focus is on map reading rather than running speed. Several of the world's top precision orienteers gathered in the historic surroundings to tackle a series of demanding navigation challenges.

Along the fortress walls, competitors frequently stopped to study the terrain. Several control flags could be seen in the landscape, but only one matched the control circle on the map exactly.

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At the start, officials welcomed the competitors while also helping curious visitors understand how the discipline works.

"The task is to decide which of the control flags you see in front of you actually matches the map. And it's very difficult," says official Ulla Lindhe of IK Stern.

For event organiser William Rex of OK Landehof, Bohus Fortress was the perfect venue for the competition.

"This is the second stage of the O-Ringen PreO competition, which also counts as a round of the Swedish Cup. Several of the world's best competitors, together with Sweden's elite, are here today. They walk along the fortress walls solving the challenges set around Bohus Fortress," he says.

The course featured around twenty control tasks. From designated viewing points, competitors had to determine which control flag was correctly placed. If several competitors finished with a perfect score, the final standings were decided by a timed control, where similar tasks had to be solved as quickly as possible.

Magnus Sterner of Strängnäs-Malmby OL, who competes regularly in the elite class, enjoyed both the course and the setting. For him, map reading is what makes PreO unique.

"It's all about really immersing yourself in map reading. I enjoy foot orienteering as well, but this is something special," says Magnus Sterner.

For William Rex, that feeling is exactly what the sport is all about.

"The best part is when everything suddenly makes sense – when the map matches the terrain and you've solved the challenge. It's a wonderful feeling when the control flags are exactly where you hoped they would be," he says.