Mercer claimed victory in a dramatic women's paddleboard distance race, contested over 18 kilometres, as she edged New Zealand's Jessica Miller on the line.

Denmark’s Katrine Zinck was also in contention right until the very end but was eventually forced to settle for the bronze medal.

"Just last night my board arrived at the airport and we discovered that there was a huge crease in it," said Mercer.

"My teammates along with friends from other competing nations stayed up late last night fixing. 

"The first time I saw my board was this morning before the race and I just had faith that things would go my way.

"To paddle for 20km and come down to a sprint finish is the toughest way to have a race go so I knew I had to be really technical and be smart, but you really want to try to push as many girls back as you can.

"I just had to win, not just for me but for my family. 

"They are going through a tough time and deserve this happiness and joy in their lives right now."

Australia's second success on the opening day in the Danish capital came when Lachie Lansdown triumphed in the men's paddleboard distance race.

Lansdown was also involved in a tight finish as he ousted defending champion Sam Shergold of New Zealand by half a board to clinch his second world title.

Hungary’s Bruno Hasulyo sealed his first gold medal at this level as he prevailed in the men's SUP distance race ahead of Hawaiian star Connor Baxter, who did enough for silver.

Baxter crossed the line in front of Hasulyo's brother Daniel, who took bronze on a superb day for the Hungarian team.

New Zealand powerhouse Annabel Anderson dominated the women's SUP distance race, moving into an early lead which proved too hot for the rest of the field to handle.

Anderson cruised to the gold medal with Sonni Honscheid of Germany and Olivia Piana of France earning silver and bronze respectively.

The event continues tomorrow with the SUP sprint races for men and women.