America's Jessica Long has taken the gold medal in the S8 400m freestyle in a world record time of 4:42.28.
Great Britain's Heather Frederiksen claimed silver, but she was more than 18 seconds off Long's pace.
Long led from the start and extended her lead through every turn, with the only question being how much she would shave off the world record.
In the end it was almost two seconds as Long took her second gold of the London Paralympics.
Maddison Elliott of Australia came home to take bronze.
