Surfing and music have always been intertwined.
From the millennia-long practices of the Kanaka Maoli, to the 19th-century Hawaiian chant of He Inoa No Nāihe, to the 1960s surf guitar of Link Wray and Dick Dale, and the famously landbound Beach Boys.
In the early 2000s, the clearest parallel between surf and song came from a subsection of folk- and blues-leaning singer-songwriters, as handy on a goofy foot take-off as a fretboard.
"Ben Harper is a musician first and he loves surfing. I'm a surfer first and I love playing music," surfer, filmmaker and singer-songwriter Jack Johnson tells Double J's Michael Hing.
"Our relationship has always been perfect. He brought me out on the first tours, but I was the one who always knew somebody in town that had surfboards and wetsuits if we needed them."
No-one from that scene travelled further than Johnson, who has sold more than 20 million albums and earned a permanent place on playlists at every cafe you've ever sat in.
In November, the two of them tour Australia together again, with John Butler, another peer from those early days, on every date.
In 2001, Johnson toured Australia for the first time, playing a couple of dates at the East Coast Blues and Roots festival, where Ben Harper was royalty, his earlier headline sets still spoken of with reverence.
"I got a better spot than I should have on the bill," Johnson says. "Ben asked for a favour, and he got me in there."
On the final night he played the slot immediately before Harper. Tens of thousands crammed into the tent for the headliner. They left as fans of the unknown support act.
He'd soon be filling arenas under his own steam, but Johnson made his gratitude clear at the time.
"I was like, 'OK, I've got to pay Ben back for taking me on tour.' So, I called up some friends and was like, 'Bring a bunch of boards down to the beach.' We got everybody in his band out in the water, and it was such a memorable day.
"Ben grew up surfing and skating, so he had a little more experience. But some of the other guys in the band, it was the first time they'd ever tried.
"Those are the kind of days, when you look back on touring and a lot of the memories you have, that I almost remember more than the show itself."
That trip began a 25-year habit: Johnson has played about 100 shows here since. Adoring crowds help. So does the sun, surf and sand.
"I always feel really at home," he says of Australia. "Anywhere surf culture is big, it's like a real natural thing for me. It's from growing up in Hawaii.
There's a neat symmetry, then, in the two artists touring Australia together again 25 years on and Johnson is still, unmistakably, a fan.
"Ben Harper was somebody I listened to for a couple of years before we ever got a chance to meet, and anytime I get a chance to do a show with Ben, I just fan out again," Johnson says.
John Butler, another peer from those years, and one of Australia's best-known roots artists, joins every date of the November tour.
"I remember showing up for a sound check at a show we were doing together," Johnson says of his first encounter with Butler.
"I hadn't heard his music much. I walked into this venue and heard somebody ripping on the guitar. I just sat there like, 'Oh, wait, I'm playing with this guy tonight?! Amazing!'"
"For me, it's not just any normal group of shows," he says. "This is a good one."
After that first Australian tour, Jack Johnson became a megastar.
When he toured his second album On and On in 2003, he headlined arenas on his own terms. None other than Hollywood A-lister Ben Stiller made the video for that album's song Taylor.
"To tell this story, I've got to be a little bit of a name-dropper," Johnson says.
"I got a chance to meet Owen Wilson and he said, 'I like your music, but I'll tell you who's kind of weird about your music: Ben Stiller.'
"He was like, 'He's a little weird. If you see him, watch out for him.'"
Stiller, fresh off Meet the Parents, Zoolander and The Royal Tenenbaums, had one of the most recognisable faces on earth. Johnson made the call anyway.
"We got to know each other a little bit. He was sweet.
"I asked him, 'Hey, I'm supposed to do a music video for this new song, and there's nothing I want to do less than have to act in a music video. You're good at that stuff. Why don't we do a video where you play me?'"
The idea was strong, but Stiller was one of the biggest film stars in the world. He was busy.
"He was like, 'I'm in the middle of shooting a film. That feels maybe too much. What about this idea: I'm a director and I want to make a video about you, but you're just too mellow and I'm disgruntled with your performance [so] I try to get you to do more.'
"A couple days after we met, we shot the video and it was all improvised. There's some outtakes from it that are really funny. The hardest part was that I couldn't keep a straight face. Every time he would make a joke, I just kept falling apart."
The video sold a lie, though, the same one his sea-swept acoustic ballads have been selling ever since: that Jack Johnson is a permanently relaxed man. The truth is not quite so simple.
"I get a rap for being mellow but I'm not that mellow," he says. "My friends always laugh at the mellow guy label, because I'm actually pretty competitive."
Jack Johnson kicks off his Australian tour in Brisbane on November 7, before shows in Perth, Sydney and Melbourne.