Pictured: Ironman athletes take to the sea in Tenby Pembrokeshire, Wales, UK. Sunday 10 September 2017
Re: The Ironman Wales triathlon has returned to Pembrokeshire for a sixth time.
More than 2,000 endurance athletes are taking on one of the most challenging courses in the sport, starting and finishing in Tenby.
It includes a 2.4 mile (or 3.8km) swim, a 112 mile (or 180km) bike ride and 26.2 mile (or 42km) run within 17 hours.