A string bikini refers to a bikini swimsuit that is scantier and more revealing than traditional bikinis. It gets its name from the string characteristics of its design. Rather than featuring a full single piece bottom, the string bikini consists of two triangular shaped pieces connected at the groin but not at the sides, where a thin "string" wraps around the waist connecting the two parts. String bikini tops are similar and are tied in place by the attached "string" pieces. String pieces can either be continuous or tied.

Monokini, sometimes referred to as a unikini, is a woman's one piece beach garment equivalent to the lower half of a bikini.^[5] The term is used for different styles of one-piece swimsuits inspired by the bikini.

In 1964, Rudi Gernreich, an Austrian fashion designer, designed the original monokini in the US.^[6] Gernreich also invented its name, and the word monokini is first recorded in English that year. Gernreich's monokini looked like a one-piece swimsuit but cut off a bit below the breasts leaving them bare. It had only two small straps over the shoulders. It was not very successful. Many women who wanted to sunbathe topless simply wore the bottom part of a bikini. Manufacturers and retailers quickly adapted to selling tops and bottoms separately

A microkini is an extremely skimpy form of a bikini. The designs for both women and men typically use only enough fabric to cover the genitalia. Any additional straps are merely to keep the garment attached to the wearer's body. Some variations of the microkini use adhesive or wire to hold the fabric in place over the genitals. These designs do not require any additional side straps to keep the garment in place. The most radical variations of the microkini are simply thin straps which cover little or none of the wearer's body. The term "microkini" was coined in 1995 in an online community dedicated to enthusiasts of the extreme designs.

Microkinis fill a niche between nudism and conservative swimwear. In addition to keeping the wearer just within legal limits of decency, they have also evolved to become the ultimate in provocative sun wear.

The tankini is a swimsuit combining a tank top and a bikini bottom of the traditional bikini that generally consists of the barest minimal fabric coverage for the top and bottoms, both are reduced to triangles of cloth connected by strings. The tankini is distinguished from the classic bikini by the difference in tops, the top of the tankini essentially being a tank top. The tankini top extends downward to somewhere between just above the navel and the top of the hips. The word is a combination of tank (as in tank top) and the end of the word bikini.

This type of swimwear is considered by some to provide modesty closer to a one piece suit with the convenience of a two piece suit, e.g. the entire suit need not be removed in order to use a lavatory. Tankinis come in a variety of styles, colors and shapes, some include features such as integrated push-up bras. A tankini for pregnant women also exists, which is divided in front exposing the navel. It is named the "peekaboo tankini".