The son of a competitive surfer from California, it would alter the course of his life. From that first trip, Naish went on to pioneer windsurfing and later kitesurfing and has become a global watersports icon.
"I was really small. It an eight-foot-long wooden boom. I could barely get it out of the water...that feeling of just, you're doing everything. Nothing works until you put it together. I just loved it."
Two years later in 1976, Naish won the first of 24 windsurfing world titles.
By the mid-1980s, as windsurfing's popularity soared, Naish had become a superstar who transcended his sport.
"He's been there since Ground Zero, back when I was a kid, he was already a world champion," said Australian Jason Polakow, a two-time wavesailing world champion.
"It's been two or three decades since that time and he's still killing it out in the waves. There are only a few people like that on the planet and he happens to be one of them."
Naish, who turns 55 on April 23, is widely regarded as one of the most influential figures in his sport, an innovator who built a multimillion-dollar brand while holding world titles across different disciplines, including windsurfing and kitesurfing.
"The guy is a multiple world champion windsurfer, but he is a cultural icon for everybody, I think, in the watersports industry," said Bernd Roediger, a two-time Aloha Classic windsurfing champion.
"People look that guy and they say, 'Oh yeah, that's Robby Naish, he's the man.'"
The charismatic Naish quickly became the poster boy for the fledgling professional circuit.
"It was amazing," Naish said. "Especially as a little kid from Hawaii that was suddenly out there, traveling the world. We had amazingly big events, in Japan and in Holland and Germany and France with hundreds of thousands of spectators and a lot of money."
Competing on the tour in the 1980s and 1990s was "like a rock'n'roll-type thing," according to Polakow.
"It was extremely popular...I remember going to my first event in Japan and Robby and all his boys were like the kings out there," he said.
When windsurfing's popularity waned after its peak in the 1980s and 1990s, Naish reinvented himself as a kitesurfer, winning more world titles in a different sport.
Having competed as a professional athlete for two decades, Naish swapped the waves for the board room when he created his own company, Naish Sails, in Hawaii in the mid 1990s.
"It kind of started small and grew organically," he said.
"My priority is still, even at this age now, that I am an athlete in my head," he said. "But this is definitely taking more time than it used to because it's not a stepping stone.
"A lot of people start a business with an exit strategy: 'I'm going to do this, and then I am going to spin it, I am going to go public and then I am going to sell it.'
"I never had that vision, this is what I do, this is the stuff we make, this is the stuff I ride."
Naish played a key role in the development of kitesurfing, which became one of the fastest-growing sports in the world in the late 1990s and 2000s.
"We were the first company to really start developing stuff that worked for kitesurfing," he said.
"I sold more kites in my first year of business, than I had sold windsurfing sails in several years combined before that. It was an amazing compliment to windsurfing. It just added a whole new dimension to being on the water."
Naish has a simple explanation for the soaring popularity of kitesurfing at the turn of the century.
"The reason it took off is, everybody wants to fly," he said. "Literally, every kid that's ever flown a kite in their life is, like, imagining flying away with this thing."
Naish's involvement with kitesurfing also helped put that sport on the map.
"Robby has a huge effect on the success of the sport," said kitesurfing pioneer Elliot Leboe.
"He has such a legendary name, I don't think kite boarding would be where it is at without Robby's involvement."
SUP and foils
In the past 10 years, Naish has been at the forefront of yet another fast-growing watersport: standup paddle boarding (SUP).
The growth of SUP in the past decade did not surprise him.
"I knew from the very beginning it was going to be huge, because it was so accessible," he said.
As for his first love, windsurfing, Naish is hoping foiling technology will give the sport a boost.
Foils, which have become the buzzword in sailing over the past decade, reduce drag and therefore boost speed as it lifts the board out of the water and allows the surfer to glide over the waves.
"Up to now, most of the foiling in windsurfing has been on the high-performance end and not much recreational," he said.
"It's only recently we've started to develop in the recreational windsurfer realm. That's where I am really pushing: to be able to go into as light a wind as possible, to bring people back into windsurfing with eight, 10 knots of wind."
Looking back on his long career, Naish said he wasn't sure what his quiet, 11-year-old self would have made of it.
"If the young Robby Naish looked at it now, he might get scared away and do something else," he said.
"I was so shy, I don't know if I could even think of all the attention. It took a long time to get to this point where I was comfortable, doing what I do."