Synchronised swimming was originally called water ballet because of its elegantly choreographed moves and fantastic costumes.
Synchro requires perfect timing with team-mates and the music
But do not be fooled by the glamour and big smiles - synchro is hard work and relies on core strength, flexibility and powerful lungs.
At the last Olympics, tests showed synchronised swimmers had the second biggest aerobic capacity behind long distance runners.
WHAT IS SYNCHRO?
Synchro is all about an athlete's ability to execute a series of movements in the pool.
Swimmers are not allowed to use the bottom of the pool for support and so stay afloat by sculling with their arms and kicking with their legs.
Swimmers must synchronise their movements to the music, which is played out though an underwater speaker.
In duet and team competitions, the swimmers also have to synchronise their moves with each other too.
There is one final key element to synchronised swimming - presentation.
Swimmers smooth their hair back with gelatin, apply waterproof make-up and their expressions must reflect the music.
So if the music is mean and moody they have to be too - those fixed grins are a popular misconception.
HOW COMPETITIONS UNFOLD
Synchronised swimming is divided into solo, duet and team competitions.
Teams are usually made up of eight swimmers.
If there are more than 12 entries in any event, then preliminaries are held, with the top 12 going through to the final.
The competition works in similar way to ice skating and gymnastics and consists of two elements - a technical and free routine.
Synchro began as a male sport in the 1800s but now only women can compete at the Olympics, Commonwealths and Worlds. Men can now only enter open competitions.
In a technical routine, competitors choose their own music but must include seven movements in the correct order, which are set by the governing body Fina.
The climax is the free routine, where competitors have between three and four minutes to wow the judges with their own selection of movements.
THE JUDGING SYSTEM
In events like the Olympics and the Commonwealth Games, medals are determined by free and technical routines, with each worth 50% of the final score.
SOME KEY MOVES
Ballet leg - floating on surface, single leg raised to 90 degrees from body
Submarine ballet leg - done while submerged so only the lower part of calf and foot are above water
Eggbeater - Powerful way of treading water (used in water polo too) - legs make alternating circular movements to produce strong upward force
Flamingo - Starting with ballet leg, draw up shin of horizontal leg. Straighten bent leg into a ballet leg double. Maintaining legs in vertical position, unroll trunk to upside down position and execute vertical descent
There are 10-14 judges sitting around the pool and they look firstly for execution of the figures. This counts the most towards the score.
They then assess the choreography, use of music, synchronisation, difficulty and manner of presentation.
Judges only give marks on what they can see above water and ignore what happens below the surface.
Scores for technical merit and artistic impression are marked out of 10, ranging from zero - for completely failed - to 10 for perfect.
The highest and lowest scores are deducted and the remaining results are divided by the number of judges minus two, and then multiplied by five.
HOW TO GET INVOLVED
If you are a confident swimmer then there is no reason why you cannot give synchronised swimming a go.
It's a growing sport in Britain and beginners work through grades from one to six, which allows them to qualify for competitions.
Synchro is governed in Britain by the Amateur Swimming Association and its website has details of how to get involved.
At an international level, Fina regulates the sport and its website has all the rules and regulations, as well as a guide explaining how to perform all the complex movements and figures from the fishtail to the flamingo.
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