Sex differences in elite swimming with advanced age are less than marathon running. An American group has studied whether the difference between men and women increasingly increasingly increases as at marathon.They examined the ranks 1-10 in the age groups 25-89 years. Men were faster than women in freestyle (12.4 ± 4.2%), back (12.8 ± 3.0%), and breast swimming (14.5 ± 3.2%), while the difference in the dolphin (16.7 ± 5.5%) was greatest. The difference in the swimming speed took as part of the top strands for freestyle, breast swimming and dolphin for all ages and routes.
Compared to Marathon, the difference in swimming was less. The study can be found under https://pubmed.ncbi.nlm.nih.gov/25648250/