FORMER national ironman champion Dean Mercer has died after a car crash on the Gold Coast.

Mercer, who won the Australian open ironman titles in 1989 and 1995, died at Gold Coast University Hospital after being rushed there by ambulance.

The Gold Coast Bulletin is reporting the 47-year-old suffered a medical condition at the wheel.

He then had a cardiac arrest in the emergency room and died.

Mercer grew up in Thirroul, near Wollongong on the NSW south coast, and competed professionally for nearly three decades.

As well as his two Australian Ironman titles he won five NSW state championships during his illustrious career. He also won two Test of the Toughest titles and the 1997 World Oceanman series.

The sports legend was first contracted to the Kellogg’s Nutri-Grain Ironman series as a 15-year-old in 1987 before he retired in 2010. Late in his career he enjoyed fierce rivalries with competitors like Caine Eckstein and Ky Hurst, while older brother Darren was also an Ironman.

Mercer was inducted into the NSW Hall of Champions in 2014 alongside names like Dawn Fraser and Don Bradman for his achievements.

In a statement, the Mercer family said he had been returning from his regular early morning training session when he died.

“Dean was an amazing husband and loving father who loved nothing more than sharing his and Reen’s love of life and love of the surf,” the statement said.

Ironman Ky Hurst - who competed against Mercer - took to Instagram to pay tribute to his good friend.

“Heavy heart today losing one of the greatest athletes of all time. Dean was someone I raced most of my career. I looked up to him as an athlete and as a friend. He was the perfect roll (sic) model in every way. My love goes out to the Mercer family,” Hurst wrote.

Dean Mercer's family issue statement following his death Dean Mercer's family issue statement following his death

Cycling legend Robbie McEwen and Olympic swimmer Jess Schipper also reacted with shock to the news.

Devastated to hear Dean Mercer, surf lifesaving legend & absolute top bloke passed away suddenly this morning. Thoughts are with his family — Robbie McEwen (@mcewenrobbie) August 28, 2017

Heartbreaking news #rip Dean Mercer thoughts go out to your family and loved ones! — Jess Schipper (@JessSchipper) August 28, 2017

In shock to hear Dean Mercer passed away suddenly this morning. Reen & family Darren, Jordie thoughts are with you — Courtney Atkinson (@courtney_akco) August 28, 2017

Coolangatta Gold legend Guy Leech paid tribute to a man he described as one of his fiercest-ever rivals.

“The Mercer family is royalty in surf lifeaving. I’m in complete shock,” Leech told The Daily Telegraph.

“He was such a tough nut, so fit, so strong, his personality was tough and strong and he was one fo our greats.”

Mercer is survived by his wife Reen, also a former champion ironwoman and his four sons.

Mrs Mercer reportedly visited the crash scene, while his children have been taken out of school to be told about the tragedy.

The crash happened at 7am (AEST).

Close mate and Kurrawa Surf Life Saving Club senior water coach Barry Newman told the Gold Coast Bulletin he last saw Mercer just last night.

“I picked him up with the family at Coolangatta airport.

“He’d been down (in Sydney) for his grandmother’s funeral.

“It’s all very fast...I’d hate to think (how Reen is) … it’s just not a good day.”

In an interview with Body and Soul in 2008, Mercer spoke of the love he had for his children.

“The boys love to help out with everything I do, they love spending time in the garage with my tools and in the garden with me. They help me with my training and carry my drink bottles and paddle - it makes them feel very special when they know they are helping.”

More to come.

andrew.koubaridis@news.com.au