As well as being a chance for the Olympic organisers to test out the course, this week’s races will also be crucial in deciding who gets to compete in Tokyo.
Team GB will take up to three male and three female individual triathletes to the 2020 Games and finishes in qualification races can help the competitors to book their seats on the plane.
As a returning medallist, Jonny Brownlee – who took silver in Rio - needs a podium finish in his event in order to meet British Triathlon’s strict criteria for re-selection.
Also looking to impress the selectors in the men's race are Alex Yee and Tom Bishop.
Alistair Brownlee, who took gold ahead of his brother in the 2016 Olympics, isn’t competing this week but could qualify through future events.