Boulderthon, presented by PUMA, has reported a sell-out of its marathon distance race ahead of the 2025 event, taking place on September 28, 2025.
Runners will be taking part in the new marathon route that features a net elevation gain cut by about 40%, going from 982 feet to 603 feet.
The event organisers are reporting record numbers across the board, with the total field expected to once again surpass previous years with an estimated 15,000 participants joining on race day. Other distances are also reportedly close to their sell-out numbers.
“Seeing the growth of Boulderthon year-after-year has been unimaginable,” said Alexa Squillaro, Event Director of Boulderthon.
“It’s been amazing helping build this event into what it is today, and I can’t thank the Boulderthon team enough for all their hard work that is paying off in tremendous ways. Boulderthon has already made its mark among US races, and we’re just getting started!”
Boulderthon, presented by Puma, offers five distances for participants to take part in, the marathon, half marathon, 10K, 5K and Kids Run.
Boulderthon’s marathon and half marathon courses take participants through different landscapes set at the foothills of the Flatirons, with views of the Boulder Reservoir, Table Mountain and Haystack Mountain along their way.
The fast, flat course features limited elevation change and multiple straightaways, making for fast race day performances. The 10K course will run participants through the streets of Boulder showcasing the town, before leading them to Downtown Boulder for the finish on Pearl Street Mall.
The second annual Heart to Heart 5K by BCH features an all-road, fast and flat experience for all participants, allowing wheelchair athletes and those utilizing wheeled vehicles, such as duo runners, to take part in the event.
