Four sports that all happen in water; swimming, water polo, synchronised swimming and diving.
In Athens all the aquatic events are taking place in the same venue, the first time this has happened.
Some controversy surrounds the aquatics venue though as it hasn't been finished. The builders didn't have time to put a roof over it, so swimmers and spectators will get very warm at the Games.
Everyone knows how the swimming works, although swimmers will have to be wary as if they make a single false start in their event they will be disqualified.
Diving takes place from a series of high boards, with judges scoring on the difficulty of the dive and the skill of completing it.
Synchronised swimming sees pairs or groups of swimmers 'dance' to music. They must complete the complicated moves at the same time to score well.
In water polo swimmers try and throw the ball into a goal, a bit like football. Amazingly, players aren't allowed to touch the sides or the bottom of the pool during the game, so they have to keep treading water.
Who are the British hopes for Athens?
In diving, synchronised pair Leon Taylor and Peter Waterfield are tipped to do well and Tony Ally is an experienced GB Olympian.
Four years ago in Sydney there were no British medallists in the pool, now things are very different.
An Australian coach called Bill Sweetenham now runs the team and after a complete reorganisation has got lots of top medal hopes.
Sarah Price and 200m world champ Katy Sexton in the women's backstroke are strong contenders, as are world 50m champ James Gibson and Darren Mew in the breastroke.
Who are the big stars?
In the men's swimming look out for Ian 'Thorpedo' Thorpe from Australia and US star Michael Phelps. Both are young and are entering lots of events to try and win multiple gold medals.
Phelps is hoping to break the record for most golds in a single Games, set by another swimmer Mark Spitz at the Montreal Olympics in 1976.
Spitz won seven gold medals. Phelps will swim in eight in Athens.