Little research has examined ultra-endurance swimming performances. The 'English Channel Swim', where swimmers have to cover a distance of 32 km between England and France represents a unique long-distance, open-water, sea-swimming challenge, and each year swimmers from all over the world try to succeed in this challenge. The best times in minutes and the nationality of successful men and women swimmers were analysed from 1900 to 2010. A total of 1,533 swimmers (455 women and 1,078 men) from more than 40 countries have successfully completed the 'English Channel Swim'. Great Britain was the country most represented, with 38% of the total, followed by the United States with 20%. Swim speed has increased progressively for both sexes (P < 0.001) but was lower for women than for men (0.68 ± 0.15 m · s⁻¹ vs 0.71 ± 0.16 m · s⁻¹ respectively, P < 0.01). However, the best annual performances did not differ between the sexes (men: 0.89 ± 0.20 m · s⁻¹; women: 0.84 ± 0.18 m · s⁻¹, P > 0.05). The results suggest that the performance of women open-water ultra-distance swimmers may be similar to that of men. Further studies investigating anthropometrical and physiological characteristics of open-water ultra-swimmers are needed to compare men's and women's open-water ultra-swim performances.