Mountain Swim Series 2019

in United States at Various Colorado Locations

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EVENT 1: Solstice Sunset Swim (June 22)

The Solstice Sunset Swim is a swim created in cooperation with the City of Longmont. Participants have the opportunity to swim either a 1.2 mile race or a 2.4 mile race as the sun is going down.

Awards will be given out to the top three finishers in each division for each race.
Divisions will be both non-wetsuit and wetsuit for both men and women.
Hope to see you in the water!

Union Reservoir
461 County Road 26
Longmont, CO

1.2 mile ($45)
2.4 mile ($55)

1.2 and 2.4 mile races start at 6:00 PM, please be at least 45 minutes early for packet pickup.

*both events held at same time

EVENT 2: Carter Lake Crossing (July 20)

The Carter Lake Crossing is a point to point crossing of Carter Lake in Colorado.
Situated at just below 5800 feet, this nearly 3 mile swim is located in one of the most picturesque lakes in Colorado.
Awards will be given out to the top three finishers in each division for each race.
Divisions will be both non-wetsuit and wetsuit for both men and women for each race.
Hope to see you there!

Carter Lake
Park at South Campground Parking

Single direction point to point swim - 3 miles ($75)

Packet pickup will begin at 5:00 AM, we recommend being there over an hour early to get a seat on the busses, which will leave at 5:45 and 6:30

EVENT 3: Chatfield Classic (August 11)

The Chatfield Classic was a new event in 2017.
It will consist of a 1 mile swim followed by a 2 mile swim.
In between the two races, there will be a short break to allow people to warm up, warm down and rest. Participants who have not swam at the Chatfield gravel pond in the past should be aware that there is a gravel bar in the middle of the lake.
The gravel bar can create some shallow and slightly technical swimming, and also adds some race character.
This event will be limited to 250 total participants.

Participants may sign up for either the 1 mile swim, 2 mile swim or both.
It will be the last event of the year for the Swim Series and overall series winners will be announced at this event.

Chatfield Lake Gravel Pond, Littleton, CO
When: 7:00 AM
Sunday August 11, 2019

1 Mile ($45)
2 Mile ($55)
Both Distances ($75)

Time cut-offs:
All swimmers must be capable of completing the distance you have entered and must be able to complete your respective event within the given cut-off time.
1 Mile - 1 hour
2 Miles - 2 hours

Each individual event will be a mass beach start.
Depending on the number of participants, there may be waves of people sent based on expected speed. People registering day-of will be included in the last wave.

Packet Pickup
Race packet pickup will begin at 5:00 AM.
Race day registration will be available if less than 250 people have signed up.

The 1 mile swim is 1 lap, the 2 mile swim is 2 laps

EVENT 4: Castle 5K/10K (August 18)

The Castle 5K/10K is a swim in its fourth year, but its first with the Mountain Swim Series. This event is the highest altitude organized marathon swim event in the country at ~8,000 feet. It is hosted at Wellington Lake, near Conifer in Colorado. Both 5K and 10K swims are available.

Wellington Lake
21843 Stoney Pass Rd, Bailey, CO 80421

8:00 AM Sunday August 18, 2019

5K ($60)
10K ($80)

Registration Closes:
11:59 PM (midnight) Monday, August 12, 2019

Time cut-offs:
All swimmers must be capable of completing the distance entered and must be able to complete the respective event within the given cut-off time.
5K – 2 hour (complete by 10:00 AM)
10K – 4 hours (complete by 12:00 PM)

We will have a mass in-the water start for each event.

Race day registration & packet pick up will begin at 6:00am and close at 7:30am.

Both 5K and 10K options are available and the two swims will occur simultaneously. Following the 10K event, the overall winners for the year will be announced and the highly coveted overall winner for the Mountain Swim Series will be announced.

Camping and other Events:

During registration, participants will have the option to reserve a camping site nearby the swim area. These sites are available if participants would like to spend the night at the lake prior to the event. The costs associated with the camping site reservations are separate from the regular registration fees. Camping site reservation fees are $30 per site per night and are available for either Friday or Saturday nights. During check-in, campers will be required to present proof that at least one member of each campsite intends on swimming in the Castle 5K/10K. Spectators may not reserve campsites.

Campers should drive through the gate across the road from the parking area and follow the signs to the "Castle 5K/10K camping." At the fork in the road, take a left. After arriving, campers should go to the camping registration table before setting up camp.

The Castle 5K/10K will be hosted at the same time as The Cliff Backyard Ultra, which is nearby. The Cliff Backyard Ultra is being co-hosted with CROWS.

From Denver: Take Highway 285 South to Bailey. Turn left on Wellington Lake RD (first major left at the bottom of the hill). Follow the road for approximately 5 miles and go past the main office and over the dam. Drive past the lake and up the small hill. Parking will be on the left. Follow the signs.

After parking, cross the road and walk through the gate. Do not drive down the road unless you intend on camping, volunteering or are a part of the Cliff Backyard Ultra. The walk from the parking area to the start of the swim is approximately 1/2 mile.

Overall, assume that the drive will take 2 hours to reach the lake from Denver.

The Location:
This race will take place at Wellington Lake:Castle Mountain Rec
Address: 21843 Stoney Pass Rd, Bailey, CO 80421
Phone: 303-838-5496

Wellington Lake is ~45 minutes from the small town of Conifer, with dirt road access. You don’t need 4-wheel drive to access the lake, but a Prius will have a harder time getting there than other types of vehicles. There are potholes.

Race Timing

Race Timing will be done by Timberline Events LLC | Finish Line Timing ( Live Results will be available at

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If you would like to volunteer, please see details at the following location:


For event-related questions, please click on the Contact the Organizers button on the left-hand side of this page.

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