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A trail race along natural routes (Tanaosri Trail) with five distances, from the 4 km family run to a 104 km route. The event will take place from December 18 to December 20, 2026 in the Suan Phueng area, Ratchaburi Province. The official page lists the starts, route lengths, elevation gain and registration prices. The official page gives requirements for running experience; before registering, check the entry conditions for your chosen start. Prices shown are for early registration and may rise once the set number of participants is reached.
Distances and Character of the Race
On the 100 km distance (Tanaosri Trail 100), runners will have to cover 104 km with 5,510 m of elevation gain. On the 50 km distance (Tanaosri The Legend 50), the actual length is 51 km, with 2,740 m of elevation gain. When choosing a start, go by the published parameters and experience requirements.
For the 25 km distance (Tanaosri Little Boy 25), the listed figures are 26 km and 1,590 m of elevation gain. The 10 km run (Tanaosri Fun Trail 10) includes a route 11 km long with 430 m of elevation gain. The 4 km family distance (Tanaosri Family Run 4) has 100 m of elevation gain.
The distance names and the length stated in them do not always match the published distance: for example, the route labeled 100K is listed as 104 km. When planning, take the stated route length into account.
When and Where
The overall event period is from December 18 to December 20, 2026. The venue is the Natural Science Park under a royal initiative (อุทยานธรรมชาติวิทยา ตามพระราชดำริสมเด็จพระเทพรัตนราชสุดาฯ สยามบรมราชกุมารี) in the Suan Phueng area of Ratchaburi Province. Race starts are listed for December 19 and December 20; the official page does not specify what is planned for December 18.
Start times are listed in Bangkok’s time:
- December 19, 09:00 — the 100 km distance (Tanaosri Trail 100).
- December 19, 06:00 — the 50 km distance (Tanaosri The Legend 50).
- December 19, 15:00 — the 4 km family run (Tanaosri Family Run 4).
- December 20, 04:00 — the 25 km distance (Tanaosri Little Boy 25).
- December 20, 07:00 — the 10 km distance (Tanaosri Fun Trail 10).
Participation Requirements and Cost
The official page lists early registration prices: 5,000 baht for the 100 km distance (Tanaosri Trail 100), 3,300 baht for the 50 km distance (Tanaosri The Legend 50), 2,200 baht for the 25 km distance (Tanaosri Little Boy 25), 1,000 baht for the 10 km distance (Tanaosri Fun Trail 10) and 300 baht for the family run (Tanaosri Family Run 4). The family distance price includes a bib number, a T-shirt and a medal. The organizer warns that the price may rise automatically when a set number of registrations is reached.
The page also lists requirements related to completed races: a trail of no less than 50 km, at least five half marathons, a trail of at least 20 km and a mini marathon. The available information does not specify which condition applies to each distance. Before paying, check the requirements for your chosen start on the official event website.
The navigation address, ways to get to the venue, the list of mandatory gear and other practical participation rules are not included in the available information. Check these with the organizer before the trip and registration.
Frequently Asked Questions ❓
When does the Ratchaburi trail take place?
The overall event period runs from December 18 to December 20, 2026. Starts for the five distances are listed for December 19 and December 20. What is planned for December 18 is not specified on the official page.
How much does participation cost?
Early registration prices range from 300 to 5,000 baht depending on the distance. The organizer says the price may rise automatically when a set number of registrations is reached.
Which distances are available?
Five routes are listed, 104, 51, 26, 11 and 4 km long. Elevation gain is published for each: from 100 m on the family distance to 5,510 m on the 100 km route (Tanaosri Trail 100).
Where does the race take place?
The venue is the Natural Science Park in the Suan Phueng area of Ratchaburi Province. The address and directions on how to get there are not included in the available information.
Conclusion
The Tanaosri Trail race offers five distances with different lengths and elevation gain, including the 4 km family route and the 104 km distance. Before registering, check the schedule, the requirements for your chosen start and the current price on the official event website.