28/02/2016 1:32 PM AEDT | Updated 15/07/2016 12:51 PM AEST

Sydney Swimmers Strip Off For 'World's Biggest' Skinny Dip

Kate Puddicombe

Scores of brave souls have stripped off for a skinny dip in Sydney Harbour in what has been labelled the world's biggest nude ocean swim.

The fourth annual Skinny Sydney -- an event that aims to "lift the human spirit" -- kicked off under clear skies on Sunday morning at nude-friendly Cobblers Beach at Middle Head, in the Sydney Harbour National Park.

The adults-only event was not a race, offering untimed 900 or 300 metre courses, with some of the funds raised going to the McGrath Foundation and the Foundation for National Parks and Wildlife.

If everybody's naked then no ones naked 🍑 #sydneyskinny 2.0 #nothingbutbeautiful #nudie

A photo posted by Tahnee Carroll / S T Y L I S T (@taper_jean_girl) on

While the event may look to be about baring it all and having a swim, its founder Nigel Marsh recently said the focus was on health and happiness.

“It’s not about nudity and it’s not a competition. The event is about leaving all pretences behind, kick-starting a new and exciting chapter in life and focusing on the things that unite us and make life worth living,” he said.

Joy, courage, acceptance, attitude, and charity were also at the heart of the swim, Marsh told The Huffington Post Australia last month.

"You'll notice one of the words I haven’t said is nudity. I know I’ve set up a nude event that isn’t about nudity, and so I understand how people immediately leap to the wrong conclusion, but it is the wrong conclusion," he said.

"You are clothed on the land, then straight away covered by the water, and you get a sarong as soon as you get out.

"There is an element of risk and obviously it’s different to every other swim because it’s a nude one but it really isn't about nudity."

Some swimmers used Instagram to share candid moments from the event.

#thesydneyskinny2016 #sydneyskinny @thesydneyskinny #nudiejuice #cobblersbeach #sydney

A photo posted by Bec (@xstitch87) on

Oh bummer 🍑🍑 #nudiejuice #sydneyskinny

A photo posted by Patrick Hudson (@pattyhud) on

In 2015, more than 1000 swimmers took part in the yearly skinny dip.

Nudity is kept to a minimum at the swim with participants banned from getting their kit off until they're on the sand.

Those getting naked must be over 18 and spectators are not allowed.