When it comes to clothing advice for women, the “rules” are endless. They range from sizeist – “avoid horizontal stripes if you have a wider frame”, to ageist – “don’t wear a crop top over 50”. Now Australia is weighing in. A council in Greater Sydney has banned thong and g-string bikinis at its public swimming pools causing outrage among pool users and stirring a wider debate about the policing of women’s bodies.

In a now-deleted post on Facebook clarifying its swim-attire rules, Blue Mountains leisure centres stated that skimpy swimwear was “inappropriate” at its facilities. The guidelines were posted after pool users queried posters at centres warning that “revealing swimwear/thongs” were not to be worn.

If an Australian council has got its knickers in a twist over swimwear guidelines, it is going against wider trends. Skin is in, with bikinis outselling traditional one-piece swimsuits and women over 45 driving the trend. Meanwhile, a thongkini has become the default uniform on the reality show Love Island and is regularly championed by celebrities including the gen Z model Bella Hadid, the singer and size inclusivity advocate Lizzo and “midlifer” Jennifer Lopez.

This is hardly the first time that women’s bottoms have been controversial. Heather Radke, the author of Butts: A Backstory, describes bottoms as holding “a complicated space in conversations of obscenity”. The author, who has tracked the cultural history of the derriere, says people “generally have a lot of complicated feelings about the butt – it is a place associated with sex and defecation and has long been tied up in questions of racial and gender categorisation and hierarchies”.

The main difference between a g-string and thong is the amount of coverage. On the skimpy scale, the g-string offers the least coverage, with a small triangle of fabric at the front and a thin string that runs between the buttocks. Meanwhile, a thong has a narrow piece of fabric at the back while a Brazilian offers an inch or two more coverage.

The Brazilian is a hot-ticket item at the British swimwear brand Away That Day. Its “Fiji” bikini bottoms, which run from a UK size 6 to 18, are a continual bestseller. The brand’s founder, Ingemae Kotze, describes them as a “fun shape that doesn’t make you feel too naked”. She credits a desire to avoid tanning lines and an increase in body confidence in powering interest in the trend.

The fast fashion company Pretty Little Thing has a dedicated “thong bikini” category on its site offering more than 50 different options. It describes the design as “a minimal style that causes maximum impact”. Next, a high street retailer typically associated with an older age demographic, sells thong bikini bottoms for £14.

This barely there brief trend mirrors underwear trends. Sales of thongs are up at Marks & Spencer, with the retailer focusing on “neater, cheekier low-rise knicker shapes” for 2025.

Twenty-eight years after Tom Ford made headlines for sending a g-string brief down the Gucci catwalk, you can pick up a similar style as a pack of five in Asda. With the continuing gen Z obsession with Y2K fashion comes the return of the visible panty line (VPL) with thongs.

The Sydneysiders aren’t the first to object to the style. In 2023, a woman was arrested for wearing a thong bikini on Myrtle beach in South Carolina, where the style is banned. In France, full-body burkinis are banned at public pools, while men must wear Speedo-style briefs. In the UK, thongs are prohibited at Alton Towers while GLL, a social enterprise that operates 240 leisure centres under the brand Better, has guidelines that stipulate “full-coverage” bikinis. While GLL doesn’t specifically mention thongs, a spokesperson says the wording “seems to imply that thongs wouldn’t be acceptable”.

Many attribute an increase in body confidence to driving sales of thongs, but Radke is not so sure. “It’s true that there are more kinds of butts that are considered ‘acceptable’ or ‘beautiful’ than, say, in the mid-90s, but we are certainly not in a place where most people feel free from beauty standards.

“For me, the thing we should be fighting is the underlying, often unconscious, tendency to rank bodies, to suggest that some of us are, essentially, more worthy than others because of the bodies that we have.”