Swim portion cancelled due to algae risk at Leeds IRONMAN event

Athletes to compete in altered bike-run race

Author: Leo ChristianPublished 16th Aug 2026

The swim practice and swim segment of Sunday's IRONMAN race in Leeds has been cancelled due to hazardous blue-green algae levels confirmed in Waterloo Lake.

The decision, made in conjunction with Leeds City Council and based on advice from the UK Health Security Agency Environmental Hazards Team, responds to high algae concentrations resulting from recent hot weather across the UK.

While this development may be disappointing for participants, IRONMAN remains committed to delivering a thrilling race day experience in Leeds.

The event will now transition to a bike-run format, featuring a 112-mile ride followed by a 26.2-mile run.

Athletes will begin with a rolling TT bike start from transition at 7:00am.

Participants are advised to check their emails for detailed information regarding Sunday's race start.

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