This ranking system was created by USA Olympian and former 25km World Champion marathon swimmer Alex Meyer. Using an unbiased and objective computer algorithm, it has been in development since 2020 with the input from several athletes, coaches, and team managers, and learnings from studying other sports rankings.
It's easy to develop a ranking system for sports like pool swimming and track & field, which involve competition that takes place in controlled environments; you can simply use an athlete's race time, or measure how high they jump or how far they throw. It's not as easy for other professional sports such as tennis, golf, and alpine skiing, yet there exists a generally agreed upon ranking system that has become an essential and established aspect of those sports. The purpose of this global ranking system for marathon swimmers is to provide value to stakeholders, especially the athletes and their coaches, and to professionalize, legitimize, and grow the sport. Learn more about the details of the ranking method here.
Every major professional sport that does not take place on a controlled field of play, or cannot be quantified in a consistent and reliable manner, has a ranking system. This is true for racing sports (alpine skiing), individual sports (golf), match sports (wrestling, tennis), and team sports (hockey, basketball). Rankings play a vital role in many aspects of sport, and can too in marathon swimming. Rankings help:
athletes and coaches understand their progress in an unbiased and empirical way
NGBs (national governing bodies) and IFs (international federations) make informed selection decisions
sponsors, NGBs, and IFs incentivize athletes monetarily or otherwise
provide engaging content for broadcast commentary and other media