When the sun rises at dawn on Friday, hundreds of St Andrews University students will brave the chilly North Sea for the annual May Dip, an undergraduate ritual said to bring good luck in exams. But the students won’t be alone at the beach. In recent years this quirky ritual has become a target for agency and freelance photographers looking to cash in on images of students in bikinis, including some who camp out overnight on the East Sands dunes near the Fife coastal path.

“It ruined my night,” said Anna, one of the students whose photo appeared in a spread published by the Scotsman. “Now when I think about that May Dip, I think about that image, and that’s it.”

Like many of her classmates, Anna hadn’t thought twice about taking part in the dip at dawn. Hours later, she was in tears after discovering a photo of herself in swimwear published online without her consent. “I clicked on it and my heart sank,” she said. “I’m quite insecure about my appearance. I was thinking: how do I get rid of this? How do I make sure no one else sees this?”

She contacted the newspaper immediately to request the image be taken down but it had already gone to print for the following day’s edition. Anna’s photograph appeared alongside dozens of others, mostly of young women, published across national newspapers including the Daily Mail, the Scotsman and the Sun.

Groups of agency and freelance photographers have become increasingly known to stake out the event, waiting in the dark with long lenses until sunrise to capture images of students running into the sea. Although they claim to be documenting the university’s tradition, the images overwhelmingly focus on female students.

“It felt like it was just girls in bikinis getting pictures taken,” Anna said. “It wasn’t a picture of the whole beach – I was in focus, and everyone else wasn’t.”

While the university warns students in advance that they may be photographed, it has no power to prevent the press from attending the event, as the dip takes place on a public beach where photography is unrestricted.

Olivia, another student whose image was published, said she spotted a man with a camera camping out on the beach the night before. “He was putting out a one-man tent, hiding in the dunes and camping there from 9pm. It just seems really wrong.” She added: “They know what they’re doing, they know exactly who they’re picking out.”

A spokesperson for the university said: “There are, and always have been, sections of the media that seek to sexualise and objectify for commercial gain the young women who attend this event. Every year ahead of May Dip, the proctor emails students with guidance to keep them safe, including a reminder that press photographers often attend the event and any images taken can go round the world.

“We abhor this practice, and it is why we have included a specific caution in communications to our students prior to the Dip. It is, however, a symptom of a much wider societal malaise which continues to enable the objectification of women, despite the clear evidence of the harm this causes.”

Reader comments beneath the photos online are often overtly objectifying. Olivia said she was disgusted by what she saw under the post she appeared in. One comment on the Daily Mail’s post read: “The 4 in the first picture are fire. Most blokes would pile in.” Another user wrote: “No hippos or tattoos, what a nice change that makes.”

Anna said: “To have comments on your body just feels really repulsive. We’re just girls on the beach in our swimsuits.”

More than 60% of adults in the UK report negative feelings about their body image. For the students as young as 18, having photos published online without their consent can be upsetting and harmful to their mental health.

Alex Chun, the president of wellbeing and community in the St Andrews students’ association, said: “I understand the fear of not being able to take something off the internet. You might not even notice that your photo is being taken. To see that later and have that immortalised by the press is anxiety-inducing.”

Anna said: “It’s quite a vulnerable position to be in. It made me feel uncomfortable. I didn’t even look at it much because I don’t want to zoom in and pick it apart.”

The Scotsman, the Sun and the Daily Mail were contacted for comment.

Names of Anna and Olivia have been changed.