Istria 100 by UTMB
Istria 100 by UTMB – 110K
Buzet → Umag
Race guide
Updated 18 July 2026
The 110K is the classic mid-distance challenge of the Istria 100 by UTMB, a 111 km point-to-point through Croatia's Istrian interior that starts in the hilltop town of Buzet and finishes on the Adriatic coast at Umag. With 3852 m of positive climb and a high point of just 1017 m, it is a race defined not by altitude but by relentless rolling terrain, karst hills, forest and vineyard tracks, and a distinctive descent from the highlands to the sea. Held in spring, the Istria 110K is known for its early-season position on the UTMB calendar and for a course that front-loads the climbing. The first half circles back through Buzet before the route tips gradually downhill toward the coast, so runners face their hardest vertical while still fresh and then must hold form across long, deceptively runnable kilometres to Umag.
The course and terrain
The 110K covers 111 km with 3852 m of ascent, running from Buzet at 78 m to Umag at 6 m on the Adriatic. Despite the low high point of 1017 m, the elevation gain is substantial and comes in repeated punchy climbs across Istria's karst hills. The route passes Prapoće at 14.8 km (502 m), Trstenik at 26.5 km (688 m), loops back to Buzet at 41.9 km (79 m), then heads coastward via Butoniga at 58.6 km (41 m), Livade at 74.1 km (17 m), Grožnjan at 89.9 km (289 m), Buje at 96.8 km (154 m) and the Umag finish at 111 km. Terrain underfoot is quintessential Istria: rocky karst trails, forest paths, gravel farm and vineyard roads, and stretches through medieval hill towns. The profile shows the bulk of the serious climbing concentrated in the first 42 km around Buzet, with the climbs to Prapoće and Trstenik being the steepest work. After the return to Buzet the course loses height overall toward the coast, but the rolling hits keep coming — the descent to sea level is gradual, not a single drop.
Where the race is won and lost
The Istria 110K is decided in its first half. From Buzet at 78 m the course climbs to Prapoće at 502 m by 14.8 km and on to Trstenik at 688 m by 26.5 km — the high ground of the race and its most sustained climbing — before dropping all the way back to Buzet at 79 m at 41.9 km. Runners who attack these opening hills too aggressively will arrive back in Buzet already cooked for the long coastal half; those who climb patiently keep something in reserve. The second, subtler crux is the long low-lying middle section through Butoniga (41 m) and Livade (17 m), where the course runs near sea level and the footing turns fast and runnable. It is tempting to push hard here, but the sting in the tail is the climb up to Grožnjan at 289 m by 89.9 km, followed by rolling ground through Buje before the final run-in to Umag. Managing pace through the flat middle so you can still lift over Grožnjan is what separates a strong finish from a grinding one.
Pacing and fuelling
The cut-offs map the race clearly: Prapoće closes Sat 10:00, Trstenik Sat 13:00, Buzet (return) Sat 17:00, Butoniga Sat 21:00, Livade Sun 01:00, Grožnjan Sun 05:00, Buje Sun 07:00, and the Umag finish Sun 11:00. The tighter early cut-offs around the Buzet loop mean you must move steadily through the climbing half, while the overnight section from Livade onward gives a longer window but demands you keep grinding through the dark. Aid stations sit at every checkpoint, with the longest carries being the roughly 15 km legs between Prapoće and Trstenik and between Butoniga and Livade. Buzet at 41.9 km and Livade at 74.1 km are crew points, making them natural places to reset, change layers and restock. Fuel heavily on the front-half climbs where you burn the most, then keep a disciplined eat-and-drink rhythm through the fast, low middle so you do not arrive at the Grožnjan climb depleted.
Conditions to expect
As an early-season Istrian race, the 110K can serve up a wide swing of conditions: mild to warm days, cold nights inland, and the possibility of rain that turns the karst trails and forest paths slick. The exposed vineyard and ridge sections offer little shade if the day is warm, while the overnight coastal stretch from Livade to Grožnjan and Buje can feel cold and damp near the water. Layering that you can shed on the climbs and add back for the night is worth planning around the Buzet and Livade crew points. Because the route is point-to-point from Buzet to Umag, plan logistics for a finish away from the start, with crew access focused at Buzet (41.9 km) and Livade (74.1 km). The mix of technical karst early and faster runnable ground later rewards shoes with reliable grip on rock that still roll well on gravel. Above all, respect the front-loaded profile — the coast is a long way off when you crest Trstenik, and the runners who finish strong in Umag are the ones who read the first 42 km correctly.
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Checkpoints & cut-offs
✓ Course data verified against the official source (2026-07-17) · official source
0 km · 78 m · —
14.8 km · 502 m · Sat 10:00
26.5 km · 688 m · Sat 13:00
41.9 km · 79 m · Sat 17:00
58.6 km · 41 m · Sat 21:00
74.1 km · 17 m · Sun 01:00
89.9 km · 289 m · Sun 05:00
96.8 km · 154 m · Sun 07:00
111 km · 6 m · Sun 11:00
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