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The triathlon runs alongside the Tour of the Dengie Cycle Sportive & Fun Ride.

The Big East Triathlon is set in an ideal location for triathlon and is great preparation for Ironman, the season ahead, or anyone in search of a new challenge. There are two distances to choose from: Challenge Distance and Middle Distance.

The event consists of an Open Water Swim in the River Blackwater, Cycle around the quiet and scenic roads of the Dengie Peninsula and finishes with an inspirational lapped Run around the sea wall and marshes passing the historic St Peters Chapel. The Big East Triathlon has already established itself as a true classic!

Review summary

1 Review
  • Course
  • Organisation
  • Atmosphere


Hannah W
"Good race, very friendly atmosphere. It was the hottest day of 2019 when we did..."
See all reviews

How to enter the Big East Triathlon

  1. Middle Distance

    Triathlon: Swim 1.6km, Bike 82km, Run 20km
    Event passed
  2. Challenge Distance

    Triathlon: Swim 0.8km, Bike 43km, Run 10km
    Event passed

Big East Triathlon routes

All course details and maps can be found at

Event Details

What’s Included

All necessary registration details will be emailed to the email address given when entering the event.

Raceday Logistics

All raceday information can be found at


Spectators can view the Swim leg, drive out into the beautiful Essex countryside to catch the triathletes on the Cycle, and view the Run leg at various locations.


There are plenty of ways to get involved and every volunteer will receive 20% OFF Race Entry for another one of our events and an Event Memento. Whether you come as a group or an individual you will be welcomed into the Dengie Events team and will no doubt have a very enjoyable experience.

To sign up as a volunteer or for more information email us now:

[email protected]

Big East Triathlon weather forecast

Partly cloudy throughout the day.

Predicted highs
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IconLight breeze possible, up to 8mph

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Big East Triathlon reviews

4 out of 5 stars

  • Course
  • Organisation
  • Atmosphere
  • Did the Middle Distance in 2019

    Good race, very friendly atmosphere. It was the hottest day of 2019 when we did it which made it feel quite challenging.
    The swim was a sea swim in the estuary - challenging with tide/ wind but well organised and marshalled.
    The ride was very flat and fast. Again, well marshalled and roads were quiet.
    Run was challenging. Half is on a trail on the beach wall - very picturesque but exposed and was punishing in sun and wind! Could have done with more frequent water stations.
    Overall would recommend, enjoyable event which was reasonably priced and ran smoothly
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