The 'Abs crack': the summer '16 bikini craze
First there was the thigh gap, then there was the 'bikini bridge' - now the latest trend, the 'abs crack', is sweeping social media in the height of bikini season.
In recent weeks, A-list celebrities, including actress Emily Ratajkowski, Victoria Secrets model Bella Hadid and Irish supermodel Stella Maxwell, have appeared with a whole new muscle to pile the pressure on women.
The new body trend dubbed the 'Abs Crack' shows off the look of an 'irrigation ditch divide' down the centre of the stomach.
But not since the worship of the thigh gap has a body 'trend' divided so many.
But is the Holy Grail of abs definition an unachievable beauty trend or does it just take a bit more work in the gym?
Ireland's top fitness models Lynn Kelly and Rosanna Davison have some words of caution before sun-worshippers become a slave to the gym to reveal the most painful-sounding part of their abdominal muscles.
As Lynn explains, the perfect line is a genetic blessing. "To me, it looks like this is how these girls' bodies are formed," she explains. "Yes, it is clear that they work out, as you need to do some form of exercise to have muscle definition, but I would say it's actually not achievable.
"Unfortunately, you don't have a choice when it comes to how your abs form. Every body is different. The only way you can have any visible abs is by sticking to a clean diet and training consistently.
"Of course, there are different exercises that you can do to target different parts of the abdomen, but we all store fat differently so that is a factor in how visible your abs are or not."
Chalking the new fitness boast down to a "silly trend", she said: "We shouldn't be comparing our bodies to other women. We should embrace our own bodies and try to be the best that we can personally be."
Meanwhile, Rosanna Davison, who has just finished her second book, Eat Yourself Fit, says she will never allow herself to be a slave to the latest body trends.
"I think you're either built that way or you're not. I am definitely not somebody who would try to alter my body shape to fit in with whatever is currently fashionable, nor would I ever encourage others to do the same."
She added: "I never compare myself to others. Social media is brilliant in so many ways, but it becomes less than healthy when you begin to compare your life, looks or body shape with others."
Paul Byrne, celebrity personal trainer at BodyByrne, says the shape is achievable but the lifestyle to do it is unsustainable long term.
"To get that definition you have to live a completely holistic nutritional healthy lifestyle. You can stay in the gym 24/7 but you have to put in 100pc dedication in the kitchen to get that strip. That is contest level and the contestants I work with all diet down to it. And that's why you don't see so many people walking around with it, because anything rare isn't easy to get. It takes a lot of hard work.
"It would take 12 weeks of a completely clean sustainable food plan. You can't even have the odd drink or snack here and there. That's why when contestants finish, they can't wait to have a burger. In saying that, I know someone who got abs tattooed on and they looked great on stage. Remember, a lot of what you're seeing on social media is Photoshopped, too. I see some of the real versions in real life and they look rubbish in comparison."