1) Synchronized swimming originated in Europe during World War II as aquatic performances but gained more popularity and prominence in the US. 2) It is an Olympic sport that combines swimming, dance, and gymnastics performed by competitors, mostly women, who perform choreographed figures and acrobatic moves set to music. 3) One of the early pioneers was Katherine Curtis who created a series of moves in the 1960s performed by 60 swimmers known as the "Modern Sirens" that are still part of synchronized swimming routines today.