Fastest swim long course 400 metres freestyle (male)
- Who
- Lukas Märtens
- What
- 3:39.96 minute(s):second(s)
- Where
- Sweden (Stockholm)
- When
- 12 April 2025
The fastest swim long course 400 metres freestyle (male) is 3 minutes 39.96 seconds, achieved by Lukas Märtens (Germany) in Stockholm, Sweden, on 12 April 2025.
Competing at the Swim Open Stockholm, Maertens beat the record of Paul Biedermann set in 2009 during the so-called “supersuit” era, when competitors were allowed to wear hi-tech non-textile swimsuits.