Custom format · 21 August 2027
Inferno Triathlon
Thun, Switzerland
The race at a glance
- Circuit
- Independent
- Organiser
- Verein Inferno Triathlon
- Distance
- Custom format
- Terrain
- Extreme
- Swim
- 3.1 km
- Bike
- 127 km
- Run
- 25 km
- Date
- 21 Aug 2027
- Registration
- Opening soon
- Swim venue
- Lake
- Bike profile
- Hilly
- Bike elevation gain
- 3,325 m
- Run profile
- Hilly
- Run elevation gain
- 2,175 m
- Entry fee, from
- CHF 530
- Altitude
- 559 m
- First edition
- 1998
Edition history
| 2026 | Held | |
|---|---|---|
| 2025 | Held | |
| 2024 | 17 Aug 2024 | Cancelled |
| 2023 | Held | |
| 2022 | Held | |
| 2021 | Held | |
| 2020 | Cancelled | |
| 2019 | Held | |
| 2017 | Held |
How the day is laid out
The swim is held in a lake. The wetsuit call is made on race morning, against the temperature measured then.
The organiser publishes 3.1 km of swimming, 127 km on the bike and 25 km of running.
The bike course is hilly, with about 3,325 m of climbing.
The run course is hilly, with about 2,175 m of climbing.
The race was first held in 1998.
This is an extreme triathlon: the course is chosen for its terrain and its climbing, not for speed, and self-sufficiency and a support crew are part of the rules.
Registration on 11 November, 333 places, a licence, a wetsuit
A full-body wetsuit is mandatory for the swim. Registration for 2027 opens on 11 November 2026 at 11:11, for 333 athletes. The race requires a licence: day licences are sold with online registration or at check-in in Oberhofen, and foreign annual licences are valid. The finish closure on the Schilthorn is strictly enforced, with a cut-off at the Schilthorntraverse feed station at 19:30. If the weather rules out the swim, a 3 km run in Oberhofen replaces it.
Source: inferno.ch, read on 2 November 2026.
Against the calendar
Where this race sits among the others
Ranks are computed across every race of the same distance.
1
races of this distance pair a hilly bike with a hilly run, out of 1. 1 share the bike profile alone.
42
races across every distance fall in August, out of 354.
160
races are held in Europe. 32 of them in the same month as this one.
Questions about this race
- When is Inferno Triathlon 2027?
- Inferno Triathlon is held on 21 August 2027 in Thun, Switzerland. Registration has not opened yet.
- How hard is Inferno Triathlon?
- The bike course climbs about 3325 m. The bike is labelled hilly and the run hilly.
- How much is the entry fee for Inferno Triathlon?
- Entries start at CHF 530 for an individual age-group entry, before service fees. Prices rise by tier as the race fills.
Where to stay
Hotels and rentals around the race venue, for the nights around race day.
Suggested stay: 19 Aug 2027 to 22 Aug 2027
The map is provided by Stay22. Bookings are made with the provider.
Races of the same distance in the same region
- RYZON Bonn Triathlon
Bonn, Germany
- Date
- 6 Jun 2027
- Distance
- Custom format
- Country
- DE
- Triathlon de Quiberon L
Quiberon, France
- Date
- 20 Jun 2027
- Distance
- Custom format
- Country
- FR
- Triathlon de l'Alpe d'Huez L
Alpe d'Huez, France
- Date
- 28 Jul 2027
- Distance
- Custom format
- Country
- FR
- Inferno Triathlon
Thun, Switzerland
- Date
- 21 Aug 2027
- Distance
- Custom format, extreme
- Country
- CH
- Allgäu Triathlon Olymp
Immenstadt im Allgäu, Germany
- Date
- 22 Aug 2027
- Distance
- Custom format
- Country
- DE
- VentouxMan – Triathlon L
Monteux, France
- Date
- 19 Sept 2027
- Distance
- Custom format
- Country
- FR
Entries are handled by the organiser
Registration and the athlete guide are on the official race page.