RIO DE JANEIRO --Katie Ledeckycompleted the sweep.
The American won the women's 800-meter freestyle final in 8:04.79, beating her own world-record time by nearly two seconds to become the second woman in history to win the 200, 400 and 800 freestyle races at the same Olympics.
It was Ledecky's fourth gold in Rio after also winning the 4x200 freestyle relay.
Jazz Carlin was a distant second (8:16.17), and Boglárka Kapás took the bronze (8:16.37).
Also Friday, Maya DiRado denied Katinka Hosszu's bid to become a four-time gold medalist at the Rio Olympics.
Hosszu got off to a blistering start and led almost the entire race. But DiRado rallied furiously on the final lap and got Hosszu at the touch to win in 2 minutes, 5.99 seconds.
Hosszu settles for silver in 2:06.05, while Canada's Hilary Caldwell took the bronze in 2:07.54.
DiRado couldn't believe what she had done in her one and only Olympics. She put her hands on her cap in disbelief when she saw he name on top of the scoreboard.
The Associated Press contributed to this report.