USMS is a national membership-operated nonprofit organization that provides membership benefits to nearly 60,000 Masters swimmers across the country.Masters swimming is an adult aquatic fitness program for individuals ages 18 to over 100, who have chosen aquatics as their means of exercise for a healthier lifestyle. U.S. Masters Swimming (USMS) programs do not discriminate between levels of ability or the individual goals of its members. There are many different types of swimmers. Some are highly competitive; others swim for fun or fitness. Many prefer open water events or triathlons; 1st Masters Swimming welcomes them all!