"My will to live completely overcame my desire to win."

That was the reaction of 19-year-old Hungarian Alfred Hajos after he won the 1200 metres freestyle at the first modern Olympic Games in Athens in 1896. He won by being the first swimmer to reach shore after a boat had left everyone in the icy waters of the Mediterranean.

Olympic swimming has come a long way, to temperature-controlled 50-metre pools, wave-killing gutters, lane markers designed to reduce turbulence, and status as one of the Games' glamour events. It is far removed from those early days.

There were the venues, from the Bay of Zea in 1896, to Paris's River Seine in 1900, to a 100-metre pool constructed inside the athletics track in 1908. Then there were the events, from a 100-metre race for Greek sailors in 1896, to underwater and obstacle races in 1900, to a "plunge for distance" in 1908. That event involved a standing dive, with contestants then remaining motionless for 60 seconds, or until their heads broke the surface - whichever came first.

COMPETITION

Women's swimming events became a regular part of the Olympic Games in 1912, and men and women now compete in 16 events each. The programme involves four different strokes across a range of distances.

Freestyle races cover 50, 100, 200, 400, 800, 1500, 10,000 metres. The 800m is for women only, the 1500m for men only. The butterfly, backstroke and breaststroke races each cover 100 and 200 metres. All four strokes are used in the 200m and 400m individual medley events.

The 4 x 100m freestyle, 4 x 200m freestyle and 4 x 100m medley relays complete the programme.

Each race has a maximum of eight swimmers. Preliminary heats in the 50m, 100m and 200m lead to semi-finals and finals based on the fastest times. In relays and individual events of 400 metres or more, the eight fastest finishers in the preliminaries advance directly to the finals.