"... David Holmes Edgar had the fastest swimming speed at 5.05 mph (US). In 1972, Mark Spitz (US) established the 100-meter record in 51.22 seconds, which needed an average speed of 4.367 mph." - Scientific American
Edgar's time would have been faster if it wasn't for a boat being driven into him from behind. He was attempting to break Henry Taylor's record of 4:57 set in 1914.
In terms of average speed over the course of a race, no one has yet broken 1 mile per hour. The current men's world record holder is Cameron van der Burgh of Australia who averaged 933 feet per minute or about 10.5 miles per hour. His time of 50:50.04 was set in 2009.
The women's record is held by Natalie Coughlin of America with her time of 49:58 set in 2009. She was using a motor on this occasion.
As far as total distance swum, these records are also held by men. They were set in 1995 and 1996 respectively by Eric Larsen of America and Chen Ning Yang of China.
A human can swim at the fastest pace of 2.29 m/s. Tom Jager established this record on March 24, 1990, in a 50-meter swimming pool in Nashville, Tennessee, with a time of 21.81 seconds. The fastest time for 100 meters in a 50-meter pool was 48.21 seconds, implying an average speed of only 2.07 m/s.
The current world record holder is Michael Phelps with a time of 50 meters is exactly 4 minutes and 39 seconds. His best time in any other length of the pool is less than one minute longer. He broke his own world record several times since 2005. In 2008, he became the first person to break the second half-minute barrier with his time of 49.19 seconds. In 2009, he improved it again to under half a minute with a time of 44.94 seconds. This makes him by far the most successful male swimmer ever.
Phelps's teammate Ryan Lochte has also been very successful in short-course events. He holds the records for the fastest 100-meter free ride (with a time of 46.11 seconds) and the fastest 200-meter free ride (with a time of 1:30.88).
Lochte and Phelps have formed a famous "duo" on the international stage - together they have won five gold medals at the 2008 Beijing Olympics and four gold medals at the 2012 London Olympics. They are the first pair of swimmers to win five gold medals at a single Olympic Games.
The average swimmer can go at a speed of roughly 2 miles per hour, which is equivalent to swimming a 50-meter length of a pool in 56 seconds. According to ESPN, Michael Phelps, the Olympic gold medalist, swims at a blistering 6 miles per hour. However, it should be noted that he primarily trains in chlorinated pools, which are easier for swimmers to navigate than natural bodies of water such as lakes or rivers.
Many people think that swimmers are human torpedoes because of how fast they can move through water. Human beings can sustain speeds up to 25 miles per hour for limited periods of time before collapsing from the stress placed on their bodies by moving so quickly through liquid. This does not mean that every swimmer can reach that maximum speed for an entire minute; some humans have experienced heart attacks at rates as high as 180 beats per minute!
The fastest animal on earth is the dolphin, who can reach speeds of 40 miles per hour or faster for short periods of time. No human has ever matched this speed, but many swimmers have reached distances beyond what animals can do, including 100 meters in under 10 seconds and 200 meters in less than 20 seconds. These achievements are remarkable considering that animals cannot breathe underwater without going into hyperbaric oxygenation, which increases the risk of cancer and other diseases. Humans can breathe underwater without difficulty.
Olympic gold champion Michael Phelps can swim the 200-meter freestyle in roughly 1.42 minutes, equating to 4.7 mph (miles per hour) or 7.6 km/h (kilometers per hour). A sailfish can go 200 meters in roughly ten seconds. That's about 30 miles per hour! Sailfish are fast creatures.
The world record for a human swimmer is held by Alexander Krikatkin with a time of 1:52.56. That's almost four minutes faster than Phelps! Mr. Krikatkin was a Soviet swimmer who competed in the 1980 Moscow Olympics. He remains the only person ever to break one minute for the entire 200-meter freestyle.
Alexander Popov is another famous long-distance swimmer from the former USSR. He holds the official European record for the 100-meter freestyle with a time of 49.58. The record has been surpassed by several swimmers since it was set in 1989, but it's still considered very good today. Popov also holds the unofficial world record for the 1500-meter freestyle with a time of 4:22.88. That's more than three minutes better than Phelps' best time!
The longest distance that anyone has ever completed swimmingly is 90 miles. This was done by Con Kolivas from Canada who covered the trip in nine hours and fifty-two minutes.