Six years ago Martyn Tann went for a stroll down to a beach north of Perth and never came home.

The only thing found after four days of searching Mullaloo Beach on April 2, 2013 was a bag containing some of his belongings.

Mr Tann, who would now be 31, was a “free spirit” according to his parents Colin and Maree.

He’s one of eight people profiled as part of Australian Federal Police’s National Missing Persons Week.

View photos Martyn Tann went missing at WA's Mullaloo Beach in April, 2013. Source: Facebook/ Let's Find Marty More

“When he was studying marine science at James Cook University in Townsville and I used to call him the ‘uni counsellor’,” Colin told Yahoo News Australia.

“He was a good listener and people often went to him with their problems.”

Colin said even though it’s been six years “it doesn’t seem long ago” that his son disappeared without a trace.

The ride which never happened

“We had a phone conversation the night before he went missing,” Colin said.

“He was staying with his cousins and looking at moving to Broome. He had a ride teed up but that fell through. The girl he was going to travel with had an injury.”

Colin said his son was frustrated. He had done a lot of travel and was looking to move on to his next adventure.

“There was nothing untoward in our conversation,” he said.

View photos Mr Tann studied marine science and did diving. His family said they don't believe he drowned at the beach. Source: Facebook/ Let's Find Marty More

Mr Tann’s parents said he planned on doing diving in Broome. The trip was meant to occur in the following days.

On April 2, Mr Tann asked his cousins if they were down for a walk to the beach.

But they were all busy.

Maree said her son was a minimalist - it was not unusual for Mr Tann to walk around without a shirt on or to go for a swim at the beach without a towel.

It’s meant tracking his movements that day from the beach has proven to be far more difficult.

Theories on where Martyn Tann is

Maree said her son “could turn his hand to anything” given he was “highly social” and “very accepting”.

“One of the questions we asked is, ‘has he gone off to join a remote Aboriginal community?’” she said.

Colin believes he also might have looked at joining a monastery.

“He had this yearning to learn so I enquired at a number of monasteries,” he said.

“He was very spiritual but I found nothing.”

View photos A view of Mullaloo Beach from the sky. Source: Getty Images (file pic) More

They added his experience as a diver meant it’s hard to believe he drowned on the day he went missing.

“The water was as still as a pond the day he went missing too,” Mr Tann’s mum said.

Mr Tann’s dad said there are “infinite possibilities” as to what could have happened to his son.

But he’s certain his son would never leave without telling the family.

His mum added while her son could survive on a desert island he’s also “very gregarious”.

“Each year goes on where he hasn’t been here and we live in hope he’ll come back,” she said.

Colin said the family are desperately trying to get closure.

“We miss him terribly,” Colin said.

“He’s our youngest son and it’s left a big hole.”

Anyone with information is encouraged to contact Crime Stoppers on 1800 333 000 or use the online reporting page.

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