Event Summary

The Castle 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 5K/10K

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

When: Swimming - Saturday, August 26, 2023 - 8:00 AM

            Camping - Friday, August 25, 2023 - Check-in from 2PM to Sunset;

Registration Close Date: Wednesday August 23, 2023 - 11:59 PM (Tee shirt not guaranteed for registrants after August 13, 2022)

2.5K Competitive Swim

5K Competitive Swim

10K Competitive 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:



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 will be the evening before at the Royal Elk Meadows Camping area at Wellington Lake and between 6:00 and 7:15 on the morning of the swim.


Pre-Registration Pricing*: 2.5k - $75, 5k - $85, 10k - $95

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. 

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 +/-).


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 swimers will be allowed to stay at a campsite.  These swimmers should be from the same group, so as to minimize potenial COVID-19 exposure pathways.  Interaction between campsites will not be permitted.  The costs associated with the camping site reservations are separate from the regular registration fees.  Camping site reservation fees are $50 per site and are available for Friday night only. Campers will need to clean around and pack up their sites no later than 2:00PM on Saturday. 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.  There is not room and the road is too rough for tow-behind or RV campers, so we ask that if you plan to camp, you bring a "truck-bed" camper or a tent. 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 through the gate 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.

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


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 includ 6.25% online registration service fee

Note: As of March 4, 2022, camping fees were increased due to increased permit and venue fees.

MSS 2023 TheCastlePRINT