Swimming is the movement by humans or animals through water, usually without artificial assistance. Swimming is an activity that can be both useful and recreational. Its primary uses are bathing, cooling, travel, fishing, escape, and sport.

Animals with lungs have an easier time floating than those without.^[1] Almost all mammals can swim by instinct, including bats, kangaroos, moles and sloths. The few exceptions include apes and possibly giraffes and porcupines. Land birds can swim or float for at least some time. Ostriches, cassowaries and tortoises can swim. Juvenile penguins drown if they accidentally fall in water since their down cover is not designed for aquatic activities.

History

Drawings from the Stone Age were found in "the cave of swimmers" near Sura, dating back to 2000 B.C. There is evidence that swimming was also a very popular sport in Greece and Rome in the original Olympic games. In 1538, Nicolas Wynman, German professor of languages, wrote the first swimming book. Competitive swimming in Europe started around 1800, mostly using breaststroke. The front crawl, then called the trudgen (now known predominantly as the "frontcrawl") was introduced in 1873 by John Arthur Trudgen, copying it from Native Americans.

Swimming was part of the first modern 1896 Summer Olympics games in Athens. In 1900, backstroke was included as an Olympic Event. In 1908, the world swimming association Federation Internationale de Natation was formed. Butterfly was first a variant of breaststroke, until it was accepted as a separate style in the 1952 Olympics. At present, there are the four recognized strokes of butterfly, backstroke, breaststroke and frontcrawl; while the IM ("Individual Medley") is a combination of all four of the strokes in a specific order. Butterfly is done first, followed by backstroke, breaststroke, and then finishing with frontcrawl. The freestyle swimming event can technically swum with any of the four strokes, however it is almost always performed with frontcrawl as it is fastest.

Non-aquatic animals

Humans do not swim instinctively, but they feel attracted to water and show a broader range of swimming movements than other non-aquatic animals. In contrast, many monkeys can naturally swim and some, like the proboscis monkey, crab-eating macaque, and Rhesus macaque swim regularly.

    

A dog swimming

Some breeds of dog swim recreationally. Umbra, a world record-holding dog, can swim 4 miles in 73 minutes, placing her in the top 25% in human long-distance swimming competitions. Although most cats hate water, adult cats are good swimmers. The fishing cat is one wild species of cat that has evolved special adaptations for an aquatic or semi-aquatic lifestyle - webbed digits. Tigers and some individual jaguars are the only big cats known to go into water readily, though other big cats, including lions, have been observed swimming. A few domestic cat breeds also like swimming, such as the Turkish Van. 

Horses, moose, and elk are very powerful swimmers, and can travel long distances in the water. Elephants are also capable of swimming, even in deep waters. Eyewitnesses have confirmed that camels, including Dromedaries and Bactrians, can swim, despite the fact that there is little deep water in their natural habitats.

Both domestic and wild rabbits can swim. Domestic rabbits are sometimes trained to swim as a circus attraction. A wild rabbit famously swam in an apparent attack on U.S. President Jimmy Carter's boat when it was threatened in its natural habitat.

The Guinea pig (or cavy) is noted as having an excellent swimming ability.. Mice can swim quite well. They do panic when placed in water, but many lab mice are used in the Morris water maze, a test to measure learning. When mice swim, they use their tails like flagella and kick with their legs.

Many species of snakes are aquatic and live their entire lives in the water, but all terrestrial snakes are excellent swimmers as well. The larger pythons and anacondas spend the majority of their time in the water; their skeletons are not able to support their body weight well on dry land. Many Beetles are able to swim, some species of diving beetle spend most of their time in the water.

Competitive swimming

The goal of competitive swimming is to be the fastest over a given distance. Competitive swimming became popular in the nineteenth century, and comprises 34 individual events - 17 male events and 17 female events. Swimming is an event at the Summer Olympic Games, where male and female athletes compete in 13 of the recognized events each. Olympic events are held in a 50 meter pool. Competitive swimming's international governing body is FINA (Fédération Internationale de Natation), the International Swimming Federation.

The four competitive strokes are the butterfly, backstroke, breaststroke, and freestyle (front crawl). While "freestyle" and "front crawl" are often used interchangeably, freestyle is the more common name and is used in almost all competitive, club-swimming or international competitions. Swimmers generally choose to swim front crawl in a freestyle event since it is the fastest and easiest stroke. Disqualification will occur if the stroke is not swum correctly, for example if the swimmer does not touch the wall with two hands during breaststroke or butterfly.

Recreational swimming

The most common purpose for swimming is recreation. Recreational swimming is a good way to relax, while enjoying a full-body workout. Several swimming styles are suitable for recreational swimming; most recreational swimmers prefer a style that keeps their head out of the water and has an underwater arm recovery. Breaststroke, side stroke, head up front crawl and dog paddle are the most common strokes utilized in recreational swimming, but the out-of-water arm recovery of freestyle or butterfly gives rise to better exploitation of the difference in resistance between air and water.

Occupational swimming

Some occupations require the workers to swim. For example, abalone divers or pearl divers swim and dive to obtain an economic benefit, as do spear fishermen.

Swimming is used to rescue other swimmers in distress. In the USA, most cities and states have trained lifeguards, such as the Los Angeles City Lifeguards, deployed at pools and beaches.

 There are a number of specialized swimming styles specially for rescue purposes (see List of swimming styles). Such techniques are studied by lifeguards or members of the Coast Guard. The training for these techniques has also evolved into competitions such as surf lifesaving.

Swimming is also used in marine biology to observe plants and animals in their natural habitat. Other sciences use swimming, for example Konrad Lorenz swam with geese as part of his studies of animal behavior.

Swimming also has military purposes. Military swimming is usually done by special forces, such as Navy SEALS. Swimming is used to approach a location, gather intelligence, sabotage or combat, and to depart a location. This may also include airborne insertion into water or exiting a submarine while it is submerged. Due to regular exposure to large bodies of water, all recruits in the United States Navy, Marine Corps, and Coast Guard are required to complete basic swimming or water survival training.

Swimming as exercise

Swimming is an excellent form of exercise. Because the density of the human body is very similar to that of water, the body is supported by the water and less stress is therefore placed on joints and bones. Swimming is frequently used as an exercise in rehabilitation after injuries or for those with disabilities.

Resistance swimming is one form of swimming exercise. It is done either for training purposes, to hold the swimmer in place for stroke analysis, or to enable swimming in a confined space for athletic or therapeutic reasons. Resistance swimming can be done either against a stream of moving water (often termed a swimming machine) or by holding the swimmer stationary with elastic attachments.

Swimming is primarily an aerobic exercise due to the long exercise time, requiring a constant oxygen supply to the muscles, except for short sprints where the muscles work anaerobically. As with most aerobic exercise swimming is believed to reduce the harmful effects of stress. Swimming can improve posture and develop a strong lean physique, often called a "swimmer's build."

Swimming lessons

In Sweden, Denmark, Norway and Finland, the curriculum for the fifth grade states that all children should learn how to swim as well as how to handle emergencies near water. Most commonly, children are expected to be able to swim 200 metres (220 yards) – of which at least 50 metres (55 yards) on their back – after first falling into deep water and getting their head under water. Even though about 95 percent of Swedish school children know how to swim, drowning remains the third most common cause of death among children.

In both the Netherlands and Belgium swimming lessons under school time (schoolzwemmen, school swimming) are supported by the government. Most schools provide swimming lessons. There is a long tradition of swimming lessons in the Netherlands and Belgium, the Dutch translation for the breaststroke swimming style is even schoolslag (schoolstroke). The children learn a variant of the breaststroke which is technically not entirely correct.

In many places, swimming lessons are provided by local swimming pools, both those run by the local authority and by private leisure companies. Many schools also include swimming lessons into their Physical Education curricula, provided either in the schools' own pool, or in the nearest public pool.

In the UK, the "Top-ups scheme" calls for school children who cannot swim by the age of 11 to receive intensive daily lessons. These children who have not reached Great Britain's National Curriculum standard of swimming 25 metres by the time they leave primary school will be given a half-hour lesson every day for two weeks during term-time.

In Canada and Mexico there has been a call for swimming to be included in the public school curriculum.