Twichell, who took second in last year's race in Pietermaritzburg, South Africa, finished first in the 2013 edition of the event with a time of 19:04. She edged Keri Anne Payne of Great Britain by 17 seconds in the win after Payne took the title a year ago.
A 2011 Duke graduate and former All-American, Twichell is the reigning U.S. national champion in the 5K and 10K open water swimming events.
Held annually at the Midmar Dam near Pietermaritzburg, South Africa, the aQuelle Midmar Mile draws swimmers from around the world. For more information about the Midmar Mile, visit the event's website at http://www.midmarmile.co.za/.