Istria 100 is a 168km ultra marathon in Buzet, Croatia. Distance: 168km. Elevation: 7,100m D+. Difficulty: brutal (Challenge Rating 56/100). DNF rate: 30%. Time limit: 45h. Surface: trail. Established 2012.
Istria 100
Buzet, Istria, Croatia
"168km through Croatia's Istrian peninsula — medieval villages, Adriatic coast, and karst mountains on the UTMB World Series."
A UTMB World Series 100-miler through Croatia's stunning Istrian peninsula, combining Mediterranean coastline with karst mountain terrain.
The Course
A 168km loop through the Istrian peninsula's interior mountains, medieval hilltop villages, and Adriatic coastline. The course combines Mediterranean karst terrain, dense forests, and technical rocky trails. Part of the UTMB World Series.
mountainous
loop
12
1,396m
6
Runner Experience
UTMB-standard aid stations with hot food, drinks, medical support, and drop bag access at major checkpoints.
Professional UTMB-style finish with crowds, announcements, and a festival atmosphere in the finish area.
Race Day Weather
14°C
6° – 22°
65%
30%
Mediterranean spring. Generally pleasant, but nights can be cold in the mountains. The Bora wind can bring sudden cooling.
Stats & Records
2012
350
38:00:00
17:38:22
Marcin Swierc (2023)
22:15:45
Katharina Hartmuth (2024)
Entry
€220
September
months
Lore & Trivia
Istria 100 by UTMB traverses the Istrian Peninsula of Croatia — a Mediterranean landscape of hilltop villages, truffle forests, and dramatic coastal cliffs where the Adriatic Sea glows turquoise below. The 100-mile course connects the best of Istria's terrain: stone-walled olive groves, dense oak forest famous for white truffles, medieval towns perched on limestone ridges, and coastal paths where the trail hugs cliffs hundreds of metres above the sea. The race has become one of Europe's most popular 100-milers thanks to Croatia's combination of stunning scenery, excellent value, and a trail running scene that is growing with infectious enthusiasm.
- ▸ 100 miles through Croatia's Istrian Peninsula.
- ▸ Part of the UTMB World Series.
- ▸ Istria is famous for white truffles — the forests you run through produce them.
- ▸ Medieval hilltop towns dot the course — runners pass through their stone gates.
- ▸ The Adriatic coast sections are spectacularly scenic.
- ▸ Croatian ultra running is booming — Istria 100 is the flagship event.
- ▸ Excellent value compared to Western European ultras.
Istria is the Mediterranean at its finest — you run through truffle forests and medieval villages while the Adriatic sparkles below.
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Frequently Asked Questions
How long is Istria 100? +
Istria 100 is a 168km (168km) ultra marathon with 7,100m of elevation gain. The course is loop on trail terrain.
How hard is Istria 100? +
Istria 100 is rated brutal with a Challenge Rating of 56/100 (Challenging). The DNF rate is 30%. Runners have 45 hours to finish.
How do I enter Istria 100? +
UTMB Index qualification through UTMB series races. Entry costs €220. with a maximum of 500 starters.
What is the weather like at Istria 100? +
Average temperature is 14°C (range 6°C to 22°C) with 65% humidity and a 30% chance of rain. Mediterranean spring. Generally pleasant, but nights can be cold in the mountains. The Bora wind can bring sudden cooling.
Are crew and pacers allowed at Istria 100? +
Crew access is allowed. Pacers are allowed after 100km. Mandatory gear is required.
What is the course record for Istria 100? +
The men's course record is 17:38:22 set by Marcin Swierc in 2023. The women's course record is 22:15:45 set by Katharina Hartmuth in 2024.
What is the average finish time for Istria 100? +
The average finish time is 38:00:00. About 350 runners finish each year. The DNF rate is 30%.
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