Altamar 66K

From Open Water Swimming Wiki

Altamar 66K was a 6-woman relay team from Mexico that holds the fastest two-way all-female relay record across the English Channel in 18 hours 59 minutes set on 10 August 2007. The first leg was in 10 hours 4 minutes from England to France and was 8 hours 55 minutes from France back to England. The swim is noted in the Guinness Book of World Records 2009.