Did you ever watch synchronized swimming routines on TV and ask yourself how it became an Olympic sport because it seems so easy? Well, you may be surprised that despite the fancy costumes and effortless lipsticked smiles of the athletes, this is quite a demanding sport. Here are some fun facts you may not know about this blend of painstakingly coordinated swimming, dance, and acrobatics that requires core strength, endurance, flexibility, breath control, and split-second timing.

 It’s an individual—and a team—sport. Although synchronized suggests at least two or more participants, this sport can involve just one athlete. The synchronized part for a solo athlete is being in sync with the music.

 This is an Olympic sport. As mentioned, synchronized swimming, also called synchro, became an Olympic Sport in 1984. This sport includes both duet and team events. Scores from technical and free routines are combined to calculate a final rank. Judges scrutinize the swimmers for perfect synchronization and execution—above and below the water’s surface—as well as the swimmers’ ability to keep their bodies high above the water, to move constantly across the pool, and for choreography to match the music’s mood.

 Synchro started out as ballet. Synchronized swimming was originally called water ballet when it debuted in the late 19th century. Once official competitions began in the 1930s, physical education instructor Katherine Curtis helped develop the water acrobatics aspect with her club the Modern Mermaids.

This is a ladies-only sport. As far as the Olympics go, synchronized swimming is an all-female sport. However, men can compete in World Aquatics competitions as well as in many European countries. Perhaps it’s only a matter of time until the Olympics follows suit.

Nose clips are a must. Even though the attire for synchronized swimming is known for being form-fitting, athletes manage to hide spare rubber nose clips in their bathing costumes should they fall out during competition. It is not unusual for the clips to fall out, be kicked off, or knocked off during a performance.

Concussions are common. Synchronized swimmers use the “eggbeater” kick to stay upright. It is a powerful kick so the athlete can get the power to lift and fly through the air to complete the acrobatic moves. Since the swimmers swim so closely together, it is not uncommon to get hit in the head.

 The performance is supposed to look effortless. To many, synchronized swimming looks simple. The athletes work hard to not let it show when they are tired, they may need air, or that their muscles may be burning. Many spend six days a week practicing—six hours in the pool and two hours on terra firma cross-training with weights, strength training, ballet, Pilates, etc.

Pay close attention the next time you watch a synchronized swimming routine. Perhaps you can try some moves in the privacy of your own pool. But don’t touch the pool liner—synchronized swimmers aren’t allowed to touch the bottom of the pool!