MILTON, Mass. – There are plenty of stories about runners getting lost in the woods, encountering each other from opposite directions, or suddenly swapping positions despite a pass never taking place during the early years of the Trail Animals “Don’t Run Boston” 50K. Those were some obvious tells that someone likely misread their map, missed a turn, or had some other navigational mishap while trying to complete the event’s unmarked course on the trails of the Blue Hills Reservation.

The Trail Animals Running Club played host to the 30th annual “Don’t Run Boston” 50K and 17th edition of the DRB 50-miler on Saturday, April 19, 2026, at the Blue Hills Reservation in Milton, Mass. Runners took on an unmarked course through the reservation, amassing around 5,700 feet of elevation gain for the 50K and nearly 7,000 feet of climbing for the 50-miler.

MILTON, Mass. – Sweat poured down Ethan Sokol’s face and soaked the light blue shirt beneath his hydration vest as he trotted into the aid station 13 miles into his adventure. A wardrobe change made little difference; the orange shirt he swapped into ultimately suffered a similar soggy fate.

The Trail Animals Running Club played host to the 29th edition of the “Don’t Run Boston” 50K and 16th edition of the DRB 50-miler on Saturday, April 19, 2025, at the Blue Hills Reservation in Milton, Mass. Runners once again took on an unmarked course through the reservation, amassing around 5,700 feet of elevation gain for the 50K and nearly 7,000 feet of climbing for the 50-miler.

The Trail Animals Running Club played host to the 29th edition of the “Don’t Run Boston” 50K and 16th edition of the DRB 50-miler on Saturday, April 19, 2025, at the Blue Hills Reservation in Milton, Mass. The following are a small sample of photos taken by MassUltra Editor Chris Wristen. For a full gallery, check out the MassUltra Flickr page.

MILTON, Mass. — In the years since 2019 when he ran his first ultramarathon, Adam Hoffman was tempted many times to run the Trail Animals Running Club’s classic “Don’t Run Boston” 50K or 50-mile race at the Blue Hills Reservation. There was plenty that appealed to Hoffman, from the low-key, no-frills nature of the event, to the technical terrain that presented an enticing challenge.

Still there was one particular detail that kept Hoffman—and many others like him—away: the course is not marked.

MILTON, Mass. – Howie Breinan gathered the crowd of runners near the starting line by Houghton’s Pond for the pre-race briefing. Breinan scanned the faces looking back at him and recognized a few, but most were a bit unfamiliar – at least at this starting line.

The 27th edition of the Trail Animals Running Club’s original event, the Trail Animals “Don’t Run Boston” 50K, took place on Saturday, April 16, 2023, at the Blue Hills Reservation in Milton, Mass. In addition, the 14th edition of the DRB 50-miler also took place. The 6 a.m. wave start enjoyed 50-degree temperatures, fog, and a little bit of light drizzle, and similar conditions greeted runners in the 8 a.m. start wave. The day was overcast throughout, humid and breezy with temperatures in the low- to mid-50s throughout the day.

The 27th edition of the Trail Animals Running Club’s original event, the Trail Animals “Don’t Run Boston” 50K, took place on Saturday, April 16, 2023, at the Blue Hills Reservation in Milton, Mass. In addition, the 14th edition of the DRB 50-miler also took place, with runners completing the 50K course and then completing an additional 19-mile loop. All photos in this gallery are by MassUltra Editor Chris Wristen.

MILTON, Mass. – A grin stretched across Howie Breinan’s face as he stood alongside 16 other runners a few dozen yards from Houghton’s Pond. It was 6 a.m., on Saturday, April 16, and a thin coating of clouds dusted the sky at this twilight hour.