Want even more? For the first time in 2025, we offered a genuine 100-kilometer ultra trail. The O-SEE 100k leads through the legendary Lusatian Mountains, with varied ups and downs, past fairytale sandstone formations, volcanic domes, and picturesque valleys. Approximately 35 kilometers run through the Bohemian part of the Lusatian Mountains towards the Naděje Reservoir near Hamr, the Kunraticer Schweiz region, Grünberg (Zelený vrch), and Limberg (Jezevčí vrch). You'll be thrilled!

The route follows marked trails. However, in accordance with trail running ethics, the run is to be completed with a degree of autonomy, meaning each runner must navigate independently using a GPX-compatible phone or a GPS watch.

Each participant must provide proof of an ultra result (at least 70 km) within the last 5 years.

50 kilometers isn't enough for you? Then our new route, the O-SEE 75k, is just the right challenge. This distance offers breathtaking scenery under the rising autumn sun in the Lusatian Mountains. Similar to the 100k, the O-SEE 75k covers approximately 25 kilometers through the Bohemian part of the Zittau/Lusatian Mountains. Get ready for an exceptional trail challenge!

The route follows marked trails. However, in accordance with trail running ethics, the run is to be completed with a degree of autonomy, meaning each runner must navigate independently using a GPX-compatible phone or a GPS watch

Not only will the over 2,000 meters of elevation gain take your breath away on what were originally the toughest and longest kilometers of the Zittau Mountains, but the spectacular views will also leave you breathless from time to time. Challenging climbs, technical downhills, and of course, plenty of fun await you on this trail gem.

The route follows marked trails. However, in accordance with trail running ethics, the run is to be completed with a degree of autonomy, meaning each runner must navigate independently using a GPX-compatible phone or a GPS watch

XTERRA European Trail Run Championship 2026 

The XTERRA O-SEE Ultra Trail will host the XTERRA European Trail Run Championship 2026 over the half marathon (XTERRA O-SEE 25k SINGLE) and marathon distances (XTERRA O-SEE 50k SINGLE).

XTERRA Trail Run World Series

The XTERRA Trail Run World Series invites runners of all levels – from passionate recreational runners to ambitious athletes – to discover the world's most beautiful and challenging trails together. From the tropical paths of the Asia-Pacific region to the majestic mountain ridges of Europe and the vast desert landscapes of the USA, this series is a global journey for all those who love to explore new places. 

Starting places for the half marathon and marathon distances of the XTERRA Trail Run World Championship will be awarded to the best individual runners in each age group at the XTERRA O-SEE 25k and XTERRA O-SEE 50k.

Further information on rankings, qualification rules and criteria can be found on the XTERRA Trail Run World Series. 

Happiness can be so simple. Over 1,000 meters of elevation gain in 25 kilometers, packed with the most beautiful trails that will get your endorphins flowing. There are few routes in the world that will bring you as much joy as this one through the stunning Zittau Mountains. Are you ready?

The route follows marked trails. However, in accordance with trail running ethics, the run is to be completed with a degree of autonomy, meaning each runner must navigate independently using a GPX-compatible phone or a GPS watch

XTERRA European Trail Run Championship 2026 

The XTERRA O-SEE Ultra Trail will host the XTERRA European Trail Run Championship 2026 over the half marathon (XTERRA O-SEE 25k SINGLE) and marathon distances (XTERRA O-SEE 50k SINGLE).

XTERRA Trail Run World Series

The XTERRA Trail Run World Series invites runners of all levels – from passionate recreational runners to ambitious athletes – to discover the world's most beautiful and challenging trails together. From the tropical paths of the Asia-Pacific region to the majestic mountain ridges of Europe and the vast desert landscapes of the USA, this series is a global journey for all those who love to explore new places.

Starting places for the half marathon and marathon distances of the XTERRA Trail Run World Championship will be awarded to the best individual runners in each age group at the XTERRA O-SEE 25k and XTERRA O-SEE 50k.

Further information on rankings, qualification rules and criteria can be found on the XTERRA Trail Run World Series website. 

Have you always wanted to try a trail run? Then this route is just right for you. Short, challenging, and intense – perfect for beginners and those who prefer shorter distances. 16 kilometers full of fun and pure running pleasure, peppered with highlights of the Zittau Mountains