1700s – Bathing becomes a popular medicinal treatment
The early bathing gown was a simple gown. There are little descriptions of this type of gown other than one chemise-type bathing gown that was full-sleeve and ankle-length and fit the body loosely. It wasn't designed for style or comfort (the fabric was wool or flannel), but rather for modesty, decency, and practicality. It makes you wonder how practical long-sleeved wool or flannel gowns could possibly be while swimming in hot weather.
1800s – Bathing becomes a popular form of exercise for women
The bathing gown was soon adapted for more functionality in the water. Needless to say, there was not much difference in practicality between the gown and the dress. In fact, more fabric was added to the dress to prevent an "incident" from happening. Even more, the dress came with its very own attire, complete with accessories: ankle-length drawers and a long-skirted dress, so fastened to the body that if the skirt washed up, nothing would be exposed; a belt to secure everything at the waist; a long-sleeved shirt, tightened at the wrist with a band; a pair of large lisle thread gloves, an oil cap, a straw hat, and gum overshoes for the feet. Of course most of this dress was made in the same woolen material as the bathing gown.
And then came the "princess style," which was the beginning of the one-piece bathing suit. Short sleeves were also permitted.
1900s – Swimming becomes more acceptable
As swimming became more acceptable, so did costumes exposing more skin. By the mid-1920s, the swimming suit, still made of knitted wool, was one-piece and allowed for short sleeves and pants to the calves (how generous!).
By the 1930s, advances in the textile industry led to rubber suits and by that time, bathing in the sun became more popular than bathing in the water.
The modern bikini
In 1946, engineer Louis Reard and fashion designer Jacques Heim in Paris came up with the idea of the bikini separately to accommodate this new trend of "bathing in the sun." Reard got the idea while temporarily running his mother's lingerie boutique, while Heim witnessed women rolling up their beachwear to get a better tan (how could you possibly tan any part of your body that was completely covered by your swimsuit?). Both introduced the idea on July 5, with Reard making the famous comment that a swimsuit couldn't be a genuine bikini "unless it could be pulled through a wedding ring."
Of course, the idea of public piece of apparel that looked more like lingerie than clothing was not immediately widely accepted America. Women were still stuck wearing the tradition one-piece until the 1950s when the Hollywood stars would use the risqué publicity associated with the bikini as an advantage. Stars like Ava Gardner, Rita Hayworth, Elizabeth Taylor, and Marilyn Monroe posed for photographs wearing them. But until the 1950s, Americans were still stuck with the woolen one-piece swimsuit and it wouldn't be until the early ‘60s that the bikini was widespread in America.
The most famous bikini
It's regarded as the most famous bikini in history and it's the most monumental moment in the history of the two-piece bathing suit. Ursula Andress, seen above in the James Bond film Dr. No, caused sales of the swimwear to skyrocket. Although the first bikini was first seen publicly at a Paris fashion show in 1946, it was Andress as "Honey Ryder" that truly popularized the skimpy bathing suit.