In recent Games sailing has been one of the strongest events for the British team, who won three golds and a silver in Sydney.
There are lots of different events, some where sailors are in boats on their own and others where they are in small teams.
The events take place in the sea in an area down the road from Athens, in one of the few Olympic venues completed long before the Games begin.
Courses are marked in the sea by a series of buoys, and competitors must be aware of their opponents and the conditions they will be sailing in.
What are the sailing classes?
49er - small boat crewed by two who have to leap about a lot. Has big sails and can go very quickly.
470 - crewed by a male and female sailor who at times have to lean way off the boat to take it where they want it to go.
Europe - a small boat that is sailed by women at the Olympics. One sailor per boat, who has to move around a lot.
Finn - a very tough boat to sail, by a single sailor. Some of the fittest sailors at the Games will be in this class.
Laser - a little boat, and every one in the fleet is supposed to be identical to all the others. An excellent test of sailing ability above everything else.
Mistral - the only windsurfing class in the Games. A huge physical challenge.
Star - crewed by two, one of the toughest boats to sail that many of the world's top sailors have competed in.
Tornado - a catamaran and the quickest boat in the Olympics. Crewed by two, will be one of the most exciting events to watch.
Yngling - making its debut at the Olympics, is sailed by three female crew.
Sonar - three-person keelboat that is used in the Paralympics and the Olympics.
2.4mr - a small, heavy boat that is often used by disable sailors.
Who are the British hopes for Athens?
All of the gold medallists from Sydney - Ben Ainslie, Shirley Robertson and Iain Percy - will be competing in Athens, although all in different classes to four years ago.
Ainslie in particular should do well, having won the world championship for his current event - the Finn class - three times since switching to it.
Who are the big stars?
Brazil's Robert Scheidt will be very tough to beat in the Laser class having won gold at the 1996 Games and silver four years later, behind Ainslie.
Siren Sundby is the sailor of the year and is in great form in the Europe class, having won seven events in a row to top the world rankings.