Marathon Swimming Australia | 4 followers on LinkedIn. Marathon Swimming Australia (MSA) is the nation’s leading authority for marathon and long-distance swimming. | Established in 1973, Marathon Swimming Australia (MSA) is the premier authority for long-distance swimming in Australia fostering community, innovation, and excellence in the sport. Our mission is to promote and elevate the sport of open water swimming across Australia. With the aim of filling the gap created by national swimming bodies that prioritize pool swimming, the organization provides a dedicated platform for open water swimmers to develop their skills, compete, and receive recognition.