How many times have you started off the year strong with your fitness goals, and then it hits spring and you wonder why you even had fitness goals in the first place? By training for a marathon or triathlon, you may keep your goals intact. We created a list of half marathons, marathons, triathlons (including sprint triathlons), and even fun runs for you to compete in. Now go on and get your run on!

Note: some of these races, particularly marathons and Ironman races, may require you to qualify with previous race times. So make sure to check before signing up. 

Half Marathon

All-Out Mardi Crawl

Photo Courtesy of All-Out Mardi Crawl Facebook

When: February 10, 9 a.m. 

 Where: 15600 W Morrison Rd, Lakewood

Cost: Before 1/27  $70 or $65 for “no swag”. After 1/27 it is $75 and $80 for walk up

The Lowdown: Grab some beads and start your year off right by running in the All-Out Mardi Crawl. Located at the base of Red Rocks Amphitheatre, this run benefits the American Lung Association. They have a 1 mile, 5K, 10K, and of course the half marathon. Plus the race offers breakfast tacos, bagels, and chocolate milk after the run.

Horsetooth Half Marathon

Photo Courtesy of Horsetooth Half Marathon Facebook

When: April 15, 8:30 a.m.

Where: Hughes Stadium- 2011 South Overland Trail, Fort Collins

Cost: January 7-February 28 $85, March 1-April 21 $95, packet pickup and race morning $110

The Lowdown: It’s definitely not the easiest course, but hey at least there is a downhill part to it and an after party with New Belgium Brewery. This will be the 45th running of the Horsetooth Half Marathon where you start at Hughes Stadium, the former home of the CSU Rams, and run along Horsetooth Reservoir. The hardest part of the race is running up “Monster Mountain” which is a 500-foot incline. If you want to challenge yourself while having a scenic view, this race is for you.

Three Creeks Half Marathon

Photo Courtesy of Racing Underground Facebook

When: April 22, 8 a.m.

Where: Hobie Hill group area, near the Cherry Creek Marina. Free runner parking will be available at Cherry Creek High School

Cost: December 1-January 31 $60, February 1-28 $65, March 1- April 10 $70, April 11-April 22 $75

The Lowdown: Run through Cherry Creek State Park with a mix of paved and dirt trails. Three Creeks Half Marathon offers a combined  “elevation gain of only 291 feet spread out over 13.1 miles as the course follows the banks of Cherry Creek, Windmill Creek, and Cottonwood Creek.”  After the race, you will also receive a pancake breakfast!

Run the Rockies

Photo Courtesy of Vertical Runner

When: June 2, 8 a.m.

Where: 1 West Main St., Frisco (parking will be here and a shuttle will take you to Copper Mountain)

Cost: Now-February 1 is $40, February 2 to May 1 is $50, May 2-June 2 is $60, Day of Registration is $65

The Lowdown: This will be the 42nd year of Run the Rockies that starts at Copper Mountain and ends at the Frisco Historic Park. All racers will get pizza from Peppino’s and a free beer from Backcountry Brewery or Outer Range Brewery. It is a beautiful run through the Rockies, but if you don’t plan on doing the half marathon they also offer a 10K too.

Boulder Rez Half Marathon

Photo Courtesy of BBSC Endurance Running

When: June 3, 7:15 a.m.

Where: Boulder Reservoir, 5565 N. 51st St., Boulder

Cost: Now-May 2 $90,  May 3-June 3 $100, Race Day $105

The Lowdown: Run around Boulder Reservoir, where you can cool off after the race with a jump into the reservoir. The Boulder Rez Half Marathon features a course is flat with only 200 feet of elevation gain and has about 1,000 participants so make sure you register early. You will also receive a goody bag and post race food. They also offer a full marathon, 3/4 marathon, and a 10K.

Black Hawk Trail Half Marathon

Photo Courtesy of Endurance Race Series

When: July 22, 7 a.m.

Where: 9467 Drew Hill Rd. Golden

Cost: $75 with a shirt, $70 without a shirt

The Lowdown: If you are looking to challenge yourself with an uphill battle, this is the half marathon for you. Black Hawk Trail Half Marathon is one of the best “hill” courses that the “Endurance Series” has to offer, you will be running through Golden Gate State Park which is between Golden and Black Hawk. You will need to sign up for this race early since it has a max of 300 people.

Georgetown to Idaho Springs Half Marathon

Georgetown, Colorado via Thinkstock

When: August 11, 8 a.m.

Where: Georgetown Lake near Frontage Rd.

Cost: January 1-February 28 $50, March 1-April 30 $65, May 1-June 30 $75, July 1-July 31 $85, Aug 1-Aug 12 $105

The Lowdown: Starting at 8,500 feet at Georgetown Lake and descending to 7,500 feet to Idaho Springs, the Georgetown to Idaho Springs Half Marathon is a high altitude course that runs alongside Clear Creek Valley. Once you finish the race, you will be given a t-shirt and a medal, with an after-party at the Clear Creek Football field.

Golden Leaf Half Marathon

Photo Courtesy of Golden Leaf Marathon Facebook

When: September 22, 8:30 a.m.

Where: 100 Elbert Ln, Snowmass Village

Cost: $80

The Lowdown:  The Golden Leaf was chosen by Trail Runner Magazine as one of “America’s 14 Most Scenic Races” and Colorado Runner Magazine’s “Best Half Marathon” in 2008.  The course consists of mountain trails and paved roads, with a peak of 9,400 feet in elevation. If you’re looking for a run in the fall with a spectacular view, this one is for you!

Rock ‘n’ Roll Half Marathon

Photo courtesy of the Rock ‘N Roll Half Marathon

When: October 21, 7 a.m.

Where: 4655 Humboldt St., Denver

Cost: $69.99

The Lowdown: Rock out while running in Denver’s Rock n’ Roll Half Marathon. The race starts and finishes at the Capital Building, and the race goes through Downtown Denver.  Each mile marker has live bands, DJ’s, Drum Lines, and more. There is also a 10K or 5K option.


The Colorado Marathon

Photo Courtesy of Kaiser Permanente

When: May 6, 6:30 a.m.

Where: The parking lot at Remington Street and Oak Street-184 S Remington St., Fort Collins
Cost: January 1-February 28 $135, March 1-May 2 $140, Expo $145
The Lowdown:  The Colorado Marathon was voted the “Best Marathon” in the mountain region for four years in a row and is a Boston Marathon qualifier. The race starts at Stove Prairie Landing and ends in Towns Square. They also offer a half marathon, 10K, 5K and a relay race.  You will need to take a bus to the race starting point, but don’t worry it’s not a school bus. There will be free beer from Odell Brewing company and an after party in Old Times Square which Coopersmith’s Poolside will be providing free pizza and beer as well.

Colfax Marathon

Photo Courtesy of

When: May 20, 6:00 am
Where: Denver’s City Park, east side of Ferrill Lake
Cost: Now-January 24 $99, January 25-March 14 $114, March 15-April 18 $129, May 15-May 16 $139, May 17-May 29 $144
The Lowdown: The Colfax Marathon is Denver’s only marathon. The race starts at Denver’s City Park and takes you through Mile High Stadium (twice) as well as Denver Fire Station #1, Sloan’s Lake and of course the iconic Colfax Avenue.When you register you also get to choose what charity you would like to run for. You will receive a technical shirt, car decal and a finisher medal. After you’ll be invited to a party at the Michelob Ultra Beer Garden located lakeside in City Park.

Vail Valor Marathon

Photo Courtesy of Vail Valor Races

When: May 28th, 8 a.m.

Where: Vail Village Rd., Vail

Cost: $65/$75/$85/$95

The Lowdown: Run for the Vail Veterans Program by participating in the sixth annual Vail Valor Marathon. The race is all on paved surfaces, which you will run through residential neighborhoods along with the Vail Bike Path. You can also participate in the half-marathon, 5-mile run/walk, and 1-mile.

Steamboat Marathon

Photo Courtesy of Steamboat Marathon

When: June 3, 7:30 a.m.

Where: Routt County Courthouse-522 Lincoln Avenue

Cost: N/A till registration opens

The Lowdown: The Steamboat Marathon was ranked as one of the “Top 10 Destination Marathons in North America,” and it’s easy to see why. Run alongside the Elk River with gorgeous views of the Rocky Mountains, and before you know it you’ll be at the finish line.

Estes Park Marathon

Estes Park via Facebook

When: June 17, 6 a.m., walkers must start at 5:30 a.m.

Where: The Dao House (formerly named Aspen Lodge), 6120 CO- Hwy 7

Cost: Now-March 31 $75, April 1- May 1 $785, May 2-June 1 $95, June 2-race day $110

The Lowdown: Run through Rocky Mountain National Park at the Estes Park Marathon.  You’ll begin with a 1,500 feet descent within the first 6.5 miles. *Bonus* There will be massages available at the end of the race.

Aspen Valley Marathon

Photo Courtesy of Aspen Valley Marathon Facebook.

When: July 14, 6 a.m.

Where: Aspen Wagner Park-419 S Mill St. Aspen 81611

Cost:$139 will increase to $159 after March 14

The Lowdown: Run along the Rio Grande Trail which follows the Roaring Fork River all the way from Aspen to Basalt. Aspen Valley Marathon offers a marathon, half marathon and a 5K with a downhill drop of 1,418 feet in elevation from start to finish. The marathon was ranked the number one marathon in Colorado worth traveling for by Flipkey/Tripadvisor, so it is definitely something worth checking out.

Pikes Peak Marathon

Photo Courtesy of Pikes Peak Marathon Facebook

When: August 19, 7 a.m.

Where: At the base of Pikes Peak in Manitou Springs-5089 Pikes Peak Hwy, Cascade

Cost: $190, registration opens March 10

The Lowdown: From Manitou Springs to the top of Pikes Peak, The Pikes Peak Marathon isn’t for the faint of heart. In fact, it is so physically demanding that all racers will need to qualify for it. If you are looking for a new challenge, and are an experienced runner then this is the marathon is for you.

Colorado Springs Marathon

Photo Courtesy of Colorado Springs Marathon Facebook

When: September 30, 7 a.m.

Where: Acacia Park-115 E Platte Ave Colorado Springs

Cost: Now-March 29 $65, March 30-May 29 $80, May 30-Aug 29 $90, Aug 30-Sept 25 $100, Sept 26-Sept 29 $115, Sept 30-packet pickup $130

The Lowdown: The Colorado Springs Marathon begins and ends in Acacia Park, participants will run all over Colorado Springs including the Olympic training center, America the Beautiful Park, Memorial Park and even Colorado College. The race also offers a half marathon and a 5k, and all participants get a free shirt and a medal.

Castle Rock Trail Festival

Photo Courtesy of Castle Rock Trail Festival Facebook

When: October 6, 8:30 a.m.

Where: 1375 W Plum Creek Pkwy, Castle Rock

Cost: $80 through June 30, $85 July 1-Sept 15, $90 after Sept 15, $95 on race day

The Lowdown: Support the Castle Rock Parks and Trails Foundation, by running in the Castle Rock Trail Festival. The race also offers a half marathon, 50K, 10K, 5K and a family LiveBig Adventure Race.


Summer Open Sprint Triathlon

When: May 19, 7:45 a.m.

Where: 461 County Rd 26, Longmont

Cost: $80 January 1st – February 29th, $85 March 1st – May 13, $90 race week

The Lowdown: Start off this triathlon season, with the Summer Open Sprint Triathlon which features a half mile lake swim, a 12.9-mile flat loop, and a 3.9 mile run on a gravel road. There are only 500 competitors, so make sure to sign up soon since it has sold out from 2010-2017.

Ironman 70.3 Boulder

Photo courtesy of Ironman on Facebook.

When: August 4, 7 a.m.

Where: Boulder Reservoir-5565 51st St., Boulder

Cost: Tier 2 $300, Tier 3 $325.00

The Lowdown: Check completing an Ironman off your list by participating in the Ironman 70.3 Boulder. Take a 1.2-mile loop swim around Boulder Reservoir, as well as a 56-mile bike and run 13.1 miles. All participants who register get a shirt, finisher medal, sling bag, finisher hat, luggage tag, timed race results, post race food and a post-race massage.

Boulder Sunrise / Sunset

Boulder, Colorado. Photo via Thinkstock

When: June 24, 6 a.m. or August 25 at 6 a.m.

Where: Boulder Reservoir- 5565 N 51 St., Boulder

Cost: Olympic Triathlon-$110, $120, $130 Sprint Triathlon-$85, $95

The Lowdown: Swim through the Boulder Reservoir in the Boulder Sunrise. You have the option to participate in the sprint triathlon or the Olympic triathlon. The Olympic Triathlon includes .93 miles of swimming, 26.4 miles of biking, and 6.2 miles of running. The Sprint triathlon includes .47 miles of swimming, 17.3 miles of biking, and 3.1 miles of running. If you want to try one later in the season, there’s the Boulder Sunset triathlon, which takes place at the end of the season on August 25.

Boulder Peak Triathlon

Swimmers in the Boulder Peak Triathlon. Photo via Thinkstock.

When: July 8, 7 a.m.

Where: Boulder Reservoir-5565 N 51 St., Boulder

Cost: Now-March 31st $125, April 1st-July 1st $135, $145 race week (if not sold out)

The Lowdown: Boulder Peak Triathlon is listed as one of the “Top 15 Most Amazing Triathlons” by The Culture Trip, so this is for sure a triathlon you don’t want to miss out on. The course consists of a 1500 meter swim, 24.8-mile bike and a 10k run.  The race is limited to only 900 competitors and has sold out 2010 to 2017.

Frisco Triathlon

Image via Frisco Triathlon

When: July 14, 9 a.m.

Where: Frisco Bay Marina- 267 Marina Rd., Frisco

Cost: Now-February 28 $50, March 1-May 31 $60, June 1-July 13 $70, day of registration $75

The Lowdown:  The Frisco Triathlon was named “Best Triathlon” in Elevation Outdoors Magazine‘s reader poll and takes a new spin on the typical triathlon by having stand-up-paddle boarding instead of swimming.  You must provide your own paddleboard, however, if you don’t have one you can rent one locally. All participants will receive a post-race meal provided by Island Grill and a free beer from New Belgium Brewery.

Evergreen Sprint Triathlon

Photo Courtesy of Racing Underground Facebook

When: July 22, 7 a.m.

Where: Evergreen Lake House, parking is at 4019 Evergreen Pkwy

Cost: Now-January 31 $70, February 1-April 30 $75, May 1-July 8 $80, July 9-July 21st $85

The Lowdown: The Evergreen Sprint Triathlon is only 20 minutes away from Denver and consists of a 750-meter swim, 12-mile bike, and a three-mile run. All participants receive a shirt, a goody bag and a post race meal which includes breakfast burritos.

Steamboat Triathlon

Photo courtesy of

When: August 12, 8 a.m.

Where: Lake Catamount, Steamboat Springs

Cost: Now-Feb 28 $110, March 1-Aug 5 $120, race week $125

The Lowdown: The Steamboat Triathlon may be arguably one of the most scenic triathlons in Colorado where racers will start and finish in Lake Catamount. Swim 1.5k in Lake Catamount, bike 24.8 miles through Yampa Valley, and run 10k around Lake Catamount. It also features a sprint distance triathlon, aquabike and duathlon.

Oktoberfest Sprint Triathlon

Union Reservoir. Photo courtesy of

When: September 23, 8 a.m.

Where: Union Reservoir, 461 County Rd. 26, Longmont

Cost: Now-April 30 $80, May 1-August 1 $85, August 2-September 16 $90, race week $95

The Lowdown: Finish off triathlon season strong with the Oktoberfest Sprint Triathlon which features a half mile lake swim,  a 12.9 mile bike, and a 3.1 mile run. Only 600 participants are allowed so register early since the race has sold out for the past 10 years. All participants will receive a shirt and goodie bags.

Fun Runs

Cupid’s Undie Run


Image via Facebook Cupid’s Undie Run

When: Feb 24, 12-4 p.m.

Where: McNichols Civic Center Building- 144 W. Colfax Ave, Denver

Cost: $40

The Lowdown: Strip down to your underwear, all for a good cause. Cupid’s Undie Run is about a mile run that benefits Neurofibromatosis, a genetic disorder that can cause tumors to grow anywhere on the body and affects 1 in every 3,000 children born. So, make sure to have a liquor blanket and run for a cure.

Runnin’ of the Green

Photo courtesy of Runnin’ of the Green

When: March 11, 10:15 a.m. for 7K, 10:35 a.m. for 2 mile

Where: 18th and Wazee St., Denver

Cost: $40

The Lowdown:  The 30th annual Runnin’ Of The Green is coming so get ready to party. It is run/walk that has been voted the best post-race party and donates money to Volunteers of America. Deck out in your St. Patty’s gear and get ready to run.


Donut Dash 5K/10K

Image via Donut Dash Facebook

When: April 28, 7:15 a.m.

Where: City Park- 1700 N York St., Denver

Cost: 5K is $25, 10K is $35, Both is $45 (prices are before April 1st)

The Lowdown: With a course that is this flat and tons of doughnuts, this may be the most enjoyable race around. But we’re not talking about just once doughnut, all finishers will get a “sleeve of frosted donuts,” on top of a race logo shirt and finish line expo with vendors and food and yes, more doughnuts.  The Donut Dash is both a 5K and 10K and will give back to charities, clubs, and organizations that create teams.

Furry Scurry

Photo courtesy of Furry Scurry

When: May 5,  7:30 a.m.

Where: Washington Park- 900 S Downing St., Denver

Cost: $50 before the event, $55 on event day

The Lowdown: Get to meet all the cute puppies and dogs that Denver has to offer at The Furry Scurry. This is a two-mile walk that benefits the pets and horses at the Dumb Friends League. There were also be some contest during the day such as the “Pet and Person Look-Alike Contest” and the “Best Pet Trick Contest”.

The Bolder Boulder

Photo courtesy of Bolder Boulder on Facebook.

When: May 28, 6:50 a.m.

Where: 30th St. and Walnut, Boulder

Cost: Depends on what kind of shirt you want, for a short sleeve it starts at $50 for early registration then increases by $5

The Lowdown: Put on your craziest outfit, and participate in Boulder’s most entertaining runs, The Bolder Boulder. From mid-race slip ‘n slide, jello shots or an unexpected beer-and-bacon stop the race is a never-ending fun run. Racers will run through Pearl Street and finish at Folsom Field where you are greeted with a beer. This year the race turns 40 years old (or 40 years “bold” as they like to put it).

Margarita Madness 5K Run

Photo Courtesy of Margarita Madness Facebook


When: June 30, 3-8 p.m.

Where: 6745 S Sante Fe Dr., Littleton

Cost: $25 for early bird registration, $45 after early bird

The Lowdown: A three-mile course, that ends with every racer drinking a margarita. The Margarita Madness 5K might be one of the best after parties to go to after a run, since they have a main stage with a live DJ playing and food trucks on site. You must be over 21 years old to register.

Bubble RUN

Image Via Facebook Bubble RUN

When: July 28, 8 a.m.

Where: Great Lawn Park Lowry, 101 N Yosemite St., Denver

Cost: $50

The Lowdown: Run through three miles of foam with this fun run. The Bubble Run has four “Foam Bogs” so be ready to be covered head to toe in colored foam. There is no timing or placement awards, just make sure to bring a plastic bag for your phone.

Tough Mudder

Photo courtesy of Tough Mudder on Facebook.

When: August 25 and 26

Where: Aspen Snowmass- 60 Carriage Way, Snowmass Village

Cost: $115 (prices will go up)

The Lowdown: The Tough Mudder will feature 10 miles with 20+ obstacle courses. If the name isn’t obvious enough, prepare to get super down and dirty and maybe wear clothes you don’t really care about. Each participant will receive a t-shirt, a headband, and a nice cold beer after completing the race. Think it’s too intense? Sign up for the Tough Mudder Half Colorado.