Surfing, move over. You've got some competition from another water sport.

The quest for fitness is driving the new worldwide popularity of stand-up paddling, enthusiasts and equipment retailers say.

Some board shapers and business owners predict a boom in stand-up paddling in the next three to five years as the sport continues to go mainstream, with all age groups and both sexes taking part.

When Paddle Surf Hawaii—a store dedicated solely to stand-up paddle boards—opened two years ago, sales hovered around five to 10 boards a month. Now 150 to 200 boards go out the door per month at prices ranging from $900 to $1,500.

Another outlet, Tropical Blends in Kakaako, has sold 1,200 stand-up paddle boards since May 2007.

“;I think we're just looking at the very tip of the iceberg,”; said owner Jim Hayes.

One advantage is that stand-up paddling requires no waves—or even an ocean.

That could give it an edge over surfing, predicts Blane Chambers, owner of Paddle Surf Hawaii in Wahiawa.

Iconic surfers like Brian Keaulana and Laird Hamilton were instrumental in the resurgence of stand-up paddling practiced by Waikiki beachboys during the 1950s. Back then, beachboys such as the late Bobby Ah Choy headed out from the famous shoreline equipped with an oar and camera to take photos of tourists learning how to surf.

Fun is still a factor, but Chambers noticed a year ago a shift in his clientele from hard-core surfers to fitness-oriented people.

“;We're about 60 percent fitness-oriented people that may do a little bit of surfing and 40 percent hard-core surfers that are just into it for the surfing,”; he said.

The sport has also spread around the world.

Containers filled with Paddle Surf Hawaii boards are being sent to Japan, Australia and Europe. On the mainland, distributors on the East Coast are ordering boards, and there are back orders for those on the West Coast, said Chambers, who projects sales to double next summer.

At Wet Feet, a store in Aina Haina that sells a wide array of stand-up paddle boards, gear, clothing and accessories, 20 percent of monthly sales are out of state, said co-owner Doug Lock. The store, which opened two years ago, also has a paddle board rental program under which rental fees can be used to go toward an individual's purchase of a stand-up paddle board.

Chambers predicts stand-up paddling will overtake surfing in popularity because it can be done on inland waters as well as the ocean. People are having fun stand-up paddling on lakes and rivers, he said.

Along with the cardiovascular benefits, the water sport offers a fun way to burn calories with a scenic view of surrounding blue water and sightings of marine life.

“;You could see turtles, all the sea life,”; said Lock. “;Being in that upright position, you have a total view of what's going on around you.”;

It is also beneficial for those with back problems and those with diabetes trying to lower their blood sugar.

“;Chiropractors and physical therapists send us people who have bad backs,”; said Clark Kormier, manager of Wet Feet. “;It strengthens your core.”;

Business owners note women account for half of their customer base. And most of those women are focused on fitness with no interest in surfing.

“;I think the fitness aspect is really valuable to a lot of women,”; said Morgan Hoesterey, 27.

Hoesterey, an avid surfer and the only woman who entered the stand-up division in the QuiksilverEdition Molokai to Oahu Paddleboard race last summer, said her body tone has changed since she undertook the sport.

“;I didn't have to go to the gym,”; she said. “;I don't really like to go to the gym. I don't like to work out. Stand-up paddling really fools you that you're not working out, but you really are.”;