The minimum distance that constitutes a marathon swim has dramatically shortened over time.
FINA and International Marathon Swimming Hall of Fame do not keep records for swims that employ thermal insulating material, drag reduction fabrics, buoyancy aids, breathing apparatus, propulsion prosthetics, etc.
Such boats can also make the challenge easier for the swimmer by blocking wind and surface chop.
Such boats also carry food and hot beverages for the swimmer to consume periodically during the swim (e.g. every 20 to 30 minutes).
The Netherlands has a rich tradition in these races, which are known in Dutch as langebaanzwemmen (literally "long-lane swimming").