Event Summary

The Castle 2.5K/5K/10K 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.  2.5K, 5K and 10K swims are available.


What: Castle 2.5K/5K/10K

Where: Wellington Lake - 21843 Stoney Pass Rd, Bailey, CO 80421

When: Swimming - Saturday, August 24, 2024 - 8:00 AM

            Camping - Friday, August 23, 2024 - Check-in from 2PM to Sunset;

            Camping - Saturday, August 24, 2024 - Check-in from 2PM to Sunset;


 We do not permit tow-behind campers or RVs (sorry, no exception)


Registration Close Date: REGISTRATION IS NOW OPEN
  • Regular Registration Pricing*: 2.5K - $90; 5K - $100; 10K - $110

Tee shirt not guaranteed for registrants after August 9, 2024

Registration Closes Wednesday August 21, 2024 - 11:59 PM

  • Friday or Saturday Night Camping: $50
  • Friday & Saturday Night Camping: $75


2.5K Competitive Swim

5K Competitive Swim

10K Competitive Swim


Sunday - NEW!!!

Wellington Reservoir SwimRun - 5K Run/1M Swim



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.

2.5K - 1 hour (complete by 9:00 AM)
5K – 2 hour (complete by 10:00 AM)
10K – 4 hours (complete by 12:00 PM)

2023 Photos:


Countdown to Event:

7 7 7 7
0 0 0 0
0 0 0 0
2 2 2 2
4 4 4 4
6 6 6 6
1 1 1 1
7 7 7 7


We will have a single large start with all swimmers for the 2.5K, 5K and 10K leaving simultaneously.

There will be Race-day Registration for people who have emailed us in the week prior to the race.  Please arrive between 6:00 and 7:00 for registration.


Packet Pickup & Parking

Packet Pickup will be between 6:00 and 7:15 on the morning of the swim at Wellington Reservoir.

An approximately 2/3-mile walk from your car parking area to the start/finish area will be required.  PLEASE COME PREPARED AND GIVE YOURSELF ENOUGH TIME TO WALK (15 MINUTES +/-).


Event and Timing

All three swims will occur simultaneously. 

Timing will be performed using traditional number, and stopwatch, in addition to a clock.  There will not be electronic chip timing at this event.

Cellular service at the lake is spotty.  Be prepared with directions and knowledge of the campsites, parking areas, event location and directions to/from event beforehand. 


Camping and Other Events

During registration, participants will have the option to reserve a camping site in the Royal Elk Meadows camping area.  These sites are available if participants would like to spend the night at the venue before the swim. Up to 4 persons will be allowed to stay at a campsite.  These people should be from the same group. The costs associated with the camping site reservations are separate from the regular registration fees.  Camping site reservation fees are $50 per site for a single night (e.g. Friday OR Saturday) or $75 for both nights. Campers will need to clean around and pack up their sites no later than 2:00PM on Saturday if leaving Saturday day and by noon on Sunday if staying on Saturday night. 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.  Spectator camping is available 90 days before the event at https://www.castlemountainrec.com/campsites.  Campers will be assigned a camping spot.  The campsites are near the parking area, so there will be parking and race organization activities the morning of the swim. Please do not camp in the parking area, which will be blocked off with tables/signs/logs/etc.

We do not permit tow-behind campers or RVs (sorry, no exception). This is because there is limited room and the road is narrow and if we let 1 in, we would have let others in.  If there were many of these, egress for parking or camping could be an issue in the event of a fire or other emergency.  Thank you for understanding. If you plan to camp, "truck-bed" campers, or tents are great options. We ask that you respect the area and the people around you, as the camping is surrounded by Colorado's beautiful Pike National Forest, which is public land.  Please avoid leaving trash and do not cut down trees for firewood.  Please leave the area in the same condition as you found it.

Campers should drive past the main office, across the dam, and take the first right to go through the swing gate.  At the fork in the road, take a left.  After arriving, campers should go to the camping registration table before setting up camp.

Camping check-in will be from 2:00 to 7:00 on Friday and on Saturday.


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.  On the right, there will be a gate.  Go through the gate.  At the fork in the road, take a left to go towards parking and camping.  Follow the signs.

After parking, you will need to walk approximately 2/3 mile to get to the start.  The walk from the parking area to the start of the swim is approximately 2/3 mile and takes 15-20 minutes.  To get to the start walk back out the road you entered until you reach the fork in the road.  Stay to the left (do not go back out the way you drove in) and go down the dirt road.  The swim will be on the right near the bottom of the hill at the lake.

Please note that participant vehicles will not be permitted to drive to the start point and must park in the designated parking area or at their reserved campsites.


Overall, assume that the drive will take 2 hours to reach the lake from Denver and that the walk will take an additional 15 minutes, after parking.

The Location

This race will take place at Wellington Lake: www.castlemountainrec.com

            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.

* Does not include 6.25% + $1.95 online registration service fee

Note: As of January 31, 2024, race and camping fees were increased due to increased permit and venue fees.


MSS Castle2024