Sharon van Rouwendaal claimed her first Olympic medal as she secured victory in the women's 10-kilometre swim off Copacabana beach.
The Dutch swimmer moved clear on the third lap of the gruelling course in the Atlantic Ocean to take the title by 17 seconds from Rachele Bruni.
Victory came in just under two hours for Van Rouwendaal, the 22-year-old showing great form in the open water after a disappointing swim in the pool earlier in the Games - where she failed to qualify for the 400 metres freestyle final.
Brazil's Ana Marcela Cunha led after the opening lap of the course, but her advantage quickly faded with Aurelie Muller taking over at the front for France.
Reigning champion Eva Risztov appeared to be well placed, but she was not able to trouble the top three as Van Rouwendaal pulled away.
Only Muller, Rachele Bruni and Poliana Okimoto could keep pace with Van Rouwendaal, but they could not deny her the title.
Bruni and Muller had a tight battle for silver, but it was the latter who edged out her Italian rival with the crucial touch.
However, Muller was subsequently disqualified at the end of the race, handing Bruni the silver and Okimoto the bronze.