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Date:
Sun, Jul 19, 2026 at 7:00 AM – 12:00 PM
Location:
5895 Lake Washington Blvd S
Seattle, Washington
98118
United States
OpenStreetMap Google Maps
Links:
seafairtriathlon.com Register at runsignup.com
Tags:
Duathlon Run Swim Triathlon

Welcome to the Seafair Triathlon!

Seattle's only triathlon will once again take place on the shores of Lake Washington at Seward Park. Offering participants multiple disciplines on a flat, fast and picturesque triathlon course in the shadows of downtown Seattle. This race is a must do for all triathletes in the northwest.

The event offers participants a unique opportunity to participate in a sprint distance triathlon or super sprint distance in an urban setting. Swimming in a protected cove, riding on closed roadways and running through Seward Park, this is the Pacific Northwest's premier triathlon.

Offering a Kids Triathlon as well, there is a distance for everyone in the family at the Seafair Triathlon! Join us in July for the Seafair Triathlon with over 1,800 health enthusiasts taking part in the event.

More multisport events nearby

  • Seattle Cherry Blossom Run [seattlecherryblossomrun.com] [Register at runsignup.com]

    Sat, Apr 18, 2026 at 6:00 AM

    Description

    BE PART OF THE LEGION OF BLOOM!

    Come run, walk, stroll, or crawl with us through Seward Park and along South Lake Washington Boulevard, surrounded by the breathtaking beauty of cherry blossoms.

    APRIL...

    BE PART OF THE LEGION OF BLOOM!

    Come run, walk, stroll, or crawl with us through Seward Park and along South Lake Washington Boulevard, surrounded by the breathtaking beauty of cherry blossoms.

    APRIL 18, 2026: 5K, 10K, & HALF-MARATHON

    2026 will offer 5K, 10K, and Half-Marathon runs! All runs will extend onto Lake Washington Blvd to take in the blossoms along the outer stretch of the park.

    We are happy to announce this year we will have parking options available within the park!

    Cross the finish line under our signature inflatable arch and celebrate spring in full bloom!

    Follow us on Facebook and Instagram, and don’t forget to tag #CherryBlossomRun in your photos and videos.

    Let’s bloom together in this exciting new chapter. We can’t wait to see you there!

    0 m from Seattle
    5895 Lake Washington Blvd S, Seattle, Washington, 98118, United States
    OpenStreetMap Google Maps

    3.1 Miles 5k 6.2 Miles 10k 13.1 Miles Run Walk

  • Earth Day Run [runsignup.com]

    Sat, Apr 18, 2026 at 10:00 AM

    Description

    Please visit https://magnusonseries.org/ for all the details.

    6.7 km from Seattle
    Seattle, Washington, 98177, United States
    OpenStreetMap Google Maps

    5k 10k 15k 13.1 Miles Run

  • All in for Autism 5K - 2026 [allinforautism.org] [Register at runsignup.com]

    Sun, Apr 26, 2026 at 7:50 AM

    Description

    The race to support kids & families with Autism Spectrum Disorder (ASD)

    Our cause is to raise awareness and funds to support children with Autism Spectrum Disorder (ASD), their families, and...

    The race to support kids & families with Autism Spectrum Disorder (ASD)

    Our cause is to raise awareness and funds to support children with Autism Spectrum Disorder (ASD), their families, and caregivers with the ultimate goal of raising their quality of life. Come join us for a morning of fun and a great cause!

    5K Run/Walk course with fun for the whole family. Dogs welcome!

    Kid’s Run! Bring the kiddos for a full family event!

    7.9 km from Seattle
    10201 NE 4th St, Bellevue, Washington, 98004, United States
    OpenStreetMap Google Maps

    1k 5k Run Walk

  • Cougar Mountain Trail Run Series (May) [cougar.seattlerunningclub.org] [Register at runsignup.com]

    Sat, May 09, 2026 at 9:00 AM

    Description

    Welcome to the 2026 edition of the Cougar Mountain Trail Run Series, put on by Seattle Running Club and Northwest Trail Runs. Our events support King County Parks, with $15 of every entry going to KC...

    Welcome to the 2026 edition of the Cougar Mountain Trail Run Series, put on by Seattle Running Club and Northwest Trail Runs. Our events support King County Parks, with $15 of every entry going to KC Parks.

    Events

    May 9: 5.1 Miles & 10.8 Miles

    9 AM start for all races, 12:00 PM cut-off (~16:40 pace for 10.8 miles)

    June 13: 5K, 8.2 Miles & 14.5 Miles

    9 AM start for all races, 1:00 PM cut-off (~16:35 pace for 14.5 miles)

    July 11: 5K, 10.8 Miles & 19.5 Miles

    9 AM start for all race, 2:30 PM cut-off (~16:55 pace for 19.5 miles)

    August 8: 5K, 14.5 Miles & 26.2 Miles

    8:30 AM start for the 14.5 and 26.2, 9 AM start for the 5K, 4 PM cut-off (~17:10 pace for the marathon)

    October 24: 5K, 7.6 Mile Cross Country, 19.5 Miles & 50K

    8 AM start for the 19.5 and 50K (7 AM early start will be available), 9 AM start for 7.6 Miles and Cross Country event, 9:30 AM start for 5K, 5 PM Cut-off (~17:25 pace for 50K, ~19:30 pace for early start)

    Series (BEST 3 OUT OF 4 RACES is eligible for awards):

    Short Series: May 5.1 Miles, June 8.2 Miles, July 10.8 Miles & August 14.5 Miles

    Long Series: May 10.8 Miles, June 14.5 Miles, July 19.5 Miles, August 26.2 Miles

    Top overall Man, Woman, and Nonbinary runners based on cumulative time will receive an award and free entry into next year's series.

    If you are a Seattle Running Club member and want to use your membership discount on the short or long series, please signup for the series using the short pass or long pass and then send the race director (races@seattlerunningclub.org) an email with your SRC member number. You will receive a partial refund within 5 business days. For all other races, please use the coupon code given to Seattle Running Club members--if you do not know the member code, please email the race director with your member number to get the code).

    Online registration closes at 11:59 PM PDT the Wednesday before each event. We will have day-of registration if you did not register in time.

    Reasons to Sign Up

    1. Well-marked trails with distances that are perfect for all experience levels

    2. Community: Surround yourself with members of the trail-running community

    3. Post-race food and libations, including beer provided by one of our Club's partner stores, Flying Lion Brewery

    4. Raise money for King County Parks: $15/runner donated to the parks

    Safety Guidelines

    If you are showing symptoms of any illness or disease, please skip this race. Email races@seattlerunningclub.org for other race options or it's a much appreciated donation!

    We Run on Native Land

    We acknowledge that our running opportunities are built on the purposeful removal of Native peoples, who have been the stewards of Seattle-area lands for thousands of years. Thus, we accept our ethical responsibility for the ongoing stewardship of the land and purposeful support of Native neighbors, colleagues, businesses, and tribes. The Muckleshoot, Duwamish, Stillaguamish, Snoqualmie, and Coast Salish are the Natives of the lands we run on.

    Photo Consent

    I understand and accept that photos/videos/illustrations may be taken of me and/or my personal property while attending/participating in Seattle Running Club (SRC) events/functions. I acknowledge and agree that such photographs or other illustrations may be used by SRC and its related entities for advertising and promotional purposes in any medium, without compensation to me. If you would prefer not to have a particular photo used, let us know and we’ll do our best to remove it right away.

    A Greener Event: Cup Free - Again, this year the series is continuing to reduce the amount of trash created during the event. We ask that runners bring a refillable water container with them on the trail to use at aid stations along the way. Our friends at Seven Hills Running, Fleet Feet Sports Seattle Ballard, and Snoqualmie Running have a variety of hydration products.

    Race Information -Thanks to runners like you, the Cougar Mountain Trail Run Series has raised over $265,000+ for King County Parks and contributed hundreds of hours of trail work. Join Seattle Running Club and Northwest Trail Runs in carrying this legacy forward and making this 22nd annual event bigger and better than ever!

    Just 15 minutes from Seattle, King County's Cougar Mountain Regional Wildland Park is one of the most popular training grounds for area trail runners and the Seattle Running Club. The course builds on itself throughout the series and brings runners through a lush forest of fern-lined single-track trails, over hills and along marshes and wetland habitats. This is a great series to supplement the training regime for a fall marathon or ultra. Cougar Mountain features rolling hills, a few moderate climbs, and a few steep but short inclines.

    The summer Short Series and Long Series races are held on the 2nd Saturday of May, June, July, and August. The Fall races are held on the last Sunday in October. Series standings are updated after each month's races and everyone competing in each successive distance is eligible for Series awards (best 3 out of 4 races is eligible for awards!). There is a participant cap and the races tend to sell out, so register early! There are NO REFUNDS!

    Seattle Running Club Discount

    If you are a member of Seattle Running Club, you should have received a discount code for 20% in the newsletter. You will need to provide your member number if you use this discount code. There are also many other discounts and benefits for being a member of the Seattle Running Club.

    No Dogs

    As much as we love our four-legged friends and family members, we are not allowed to have dogs at our event. Very important announcement: Dogs are not allowed on the course due to Insurance Requirements. Despite the park's policy on dogs on leashes being acceptable, insurance has determined dogs on course cause a potentially unsafe environment for participants and spectators.

    Awards

    The top 3 Men, Women, and Nonbinary Runners in each event will receive a podium prize.

    8.7 km from Seattle
    Bellevue, Washington, 98006, United States
    OpenStreetMap Google Maps

    5.1 Miles 10.8 Miles Run Trail Ultra

  • Unity Loop 5K [runsignup.com]

    Sun, May 10, 2026 at 9:00 AM

    Description

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    5.6 km from Seattle
    800 Occidental Ave S, Seattle, Washington, 98134, United States
    OpenStreetMap Google Maps

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