Masters swimming is an organized program of swimming for adults.
Members participate in a variety of ways ranging from lap swimming to international competition.
Anyone 19 or over can join Masters swimming. U. S. Masters Swimming has over 30,000 members, a few of whom are in their 90's and even 100's. There are over 450 local Masters Swim Clubs throughout the country and more forming every day. There's probably a group accessible to you regardless of where you live.