Managers at the leisure centre in the city of Kalmar, where the “Tafsvakten” group was started, say only one assault has been reported in recent months but founder Siri Bernhardsson claims women are becoming too afraid to visit.
“The more I read, the more angry I get,” she told the Kvällsposten newspaper.
“It cannot be right that women and families should be too intimidated to go to the swimming pool, of all places. It's not a dark alley or scary nightclub.”
The 24-year-old is co-ordinating volunteers and collecting donations to cover transport, food and swimming pool entry through her “Tafsvakten” Facebook page.
It was set up on 4 February and has since garnered more than 2,000 likes, as well as pledges from women in towns and cities across Sweden to set up similar patrols.
“The news is completely overflowing with articles about molestation and rapes at Sweden's bathhouses,” Ms Bernhardsson’s mission statement reads. “I've had enough! I want to give my support.”
But the initiative has been controversial, seeing her accused of vigilantism, racism and xenophobia, as well as inciting hate towards more than 160,000 asylum seekers who arrived in Sweden last year.
The Scandinavian country, which has the highest number of refugees per capita in Europe, is known for its humanitarian policies but is now planning to deport tens of thousands of asylum seekers after introducing border controls and slashing benefits.
Public opinion has shifted following reports that police covered up widespread sexual assaults by teenage migrants at a Swedish music festival and alleged attacks by male asylum seekers at a public swimming pool in Stockholm.
News of a 10-year-old boy being raped by an Iraqi refugee at a leisure centre in Austria and sexual harassment at pools in several German towns have fuelled fears.
Ms Bernhardsson told the 24 Kalmar website that she and other women would conduct their swimming patrol in Kalmar 11am to 3pm on Saturdays and “keep their eyes open”.
“We will keep a low profile,” she added in an interview with Aftonbladet. “We are not there to act as police, but to observe and be available if someone wants to talk.”
But the pool’s manager, Susanne Gryfelt, has not welcomed the intervention.
Saying she had received no reports of women and families feeling too afraid to swim, she added: “We do not want individuals to come in and act as lifeguards – that is our job.”
Ms Bernhardsson insisted her “completely apolitical” group would work with authorities and hit out at “censorship” and criticism on Facebook.
“I started this initiative in an attempt to do good,” she added.
Police across Europe have warned against the rise of vigilante groups, who have been linked to attacks on refugees in some areas.
In Cologne, 11 asylum seekers were beaten by a mob roving the German city after vowing to “clean it up” in January, while a far-right group calling themselves the Soldiers of Odin has started up in Finland.
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