About This Event
Istria 100 by UTMB has grown from its 2013 inception to become one of Europe's most diverse trail running gatherings, attracting over 3,000 runners from around the world to Croatia's Istria Peninsula each spring. The event showcases every facet of this remarkable region, weaving together difficult technical terrain with elements of coasteering, passages through ancient medieval towns, and deep forest single track. The courses traverse muddy valleys, crystal-clear streams and brooks, dramatic canyons, and city centers, creating a unique running experience that combines natural beauty with cultural immersion. As part of the UTMB World Series, the event maintains the high standards expected from this prestigious trail running network while celebrating the distinctive character of Istrian landscapes. With five distinct distances ranging from 21K to 168K, the event offers something for every level of trail runner, from those seeking their first taste of technical terrain to ultrarunners pursuing one of Europe's most comprehensive trail challenges.
Choose Your Distance
21K
A half marathon introduction to Istrian trails with gentle elevation profile. Perfect for runners new to technical terrain while still experiencing the region's natural beauty and cultural elements.
42K
The route traverses the interior of the Istrian peninsula, linking hill towns and forested valleys through a network of singletrack trails and rural paths. Runners pass through medieval settlements where stone architecture dates back centuries, then descend into wooded canyons where seasonal streams carve through the karst landscape. The terrain alternates between exposed ridgelines offering views across the Adriatic and shaded forest sections on narrow, root-laced trails.
69K
The route traces a path through Istria's interior and coastal zones, transitioning between Mediterranean vegetation near the coast and thick forest sections inland. Runners encounter a mix of narrow single track, forest trails, and occasional gravel roads. The technical sections demand attention—exposed roots, rocky passages, and uneven surfaces are consistent features throughout.
110K
The 110K route showcases Istria's geographic diversity, moving between coastal-influenced lowlands and forested interior plateaus. Runners pass through working villages where stone architecture dates to Venetian rule, offering cultural immersion alongside the physical challenge. The course's technical character stems from natural karst terrain—porous limestone creating rocky, uneven surfaces that require constant attention to foot placement. Forest sections provide shade and softer ground underfoot, while open ridge passages offer views across the peninsula before descending back into valley systems where ancient trade routes once connected coastal ports to interior settlements.
168K
The 168K follows a loop format through Istria's interior and coastal zones. Expect technical singletrack with mud potential, rocky coastal paths, stream crossings, and forested sections that can remain cool even as coastal temperatures rise. The route connects several small towns and aid stations, providing regular support but requiring self-sufficiency between checkpoints.