Pentathletes usually have a swimming background, which is considered to be the only pentathlon discipline that cannot be taught at a higher level at an older age. For this reason, good swimming standards are considered to be a "precondition” for participation in Modern Pentathlon. The swimming event is a freestyle race over 200m for men and women with athletes seeded in heats according to their personal best time. A time of 2:30 earns 1000 Pentathlon points. Every 0.33 seconds is worth +/- 4 points and thus the value of each swimming second is worth 12 points. Example: the time 2:32.66 minutes corresponds to 968 points. Forty point penalties are incurred for a false start, failing to touch the wall at the end of a lap or leaving the pool in an incorrect manner as stipulated in the rules.
Do to limited capacity this event is invitation only.
Source: http://en.wikipedia.org/wiki/International_Modern_Pentathlon_Union