A British woman died during the swim section of an Ironman triathlon in Spain.
Sharon Lang, 39 from Plymouth, Devon is understood to have had a heart attack during the swim on Sunday.
She died in a nearby hospital the following day surrounded by her family and friends.
Her best friend Kirsty Prowse said Mrs Lang was "passionate about sports" and had "touched the lives of so many people".
The Ironman 70.3 Marbella consists of a 1,900m (6,230ft) swim, followed by a 90km (56 mile) cycle and a half marathon.
She had previously run two full marathons, numerous biking events, open water swims and seven triathlons, but this was her first Ironman event.
Ms Prowse, who travelled with Mrs Lang to support her in the event, said: "It was her dream to combine all three disciplines and compete in the Marbella Ironman.
"She trained incredibly hard for the event, often being in the pool at 6am ready to start the day, she even cycled to the Tavistock half marathon this year, completed the race and cycled home again, everyone was in awe of her."
She described her friend as "an incredibly warm young lady who constantly had a smile on her face and a positive outlook on everything she did."
The organisers of the event confirmed the death and said: "Our condolences go out to the athlete's family and friends, whom we will continue to support.
"We are working with the local authorities to gather all the details on how this incident occurred and will continue to do everything possible to provide a safe environment for our athletes."
Brian King, president of the Plymouth Musketeers Running Club where Mrs Lang was ladies captain, said she was "an inspiration" and the Marbella race was her "dream event".
The club is holding a number of memorial runs and creating an annual trophy in her name.