The ocean is so vast, and frankly, all we see is just the top of it. But it isn’t infinite. As the saying goes, you can’t wash dirty water.

Surfers have an intimate relationship with the ocean. And so, after half a century of using artificial chemical formulas to create surfboards, some surfers are looking at ways to get back to more natural wave-riding — or at least lessen their chemical footprint upon the ocean.

A new surfing exhibition has opened at Bishop Museum, and while you’re there, look for some surfboards that appear to be made of bark strips.

"These boards were totally trashed, headed for the Dumpster," explained Paul Goo of Virtual Surf Hawaii. "We thought, ‘How can we save them, using natural materials?’"

Goo’s company sets up "virtual surfing" rides for trade shows and events. Goo, who helped design games for Atari and Nintendo, ties a surfboard with balance sensors to a computerized wave that tests the rider’s balance and control. It’s on dry land, but the rider still has to control the attitude of the board — and it has to be a real board.

His interest in recycling used boards for simulators led to a larger mission. Can older boards made of chemical foam and Fiberglas laminate, hammered with dings and reticulated with cracks, be brought back up to speed with more natural materials? "Eco-friendly" repairs that don’t involve resins and glass cloth?

Goo, you understand, is an inveterate tinkerer and recycler. He makes radio-controlled airplane models out of discarded pizza boxes. Goo began to experiment, which led to the bark boards. "China started making inexpensive epoxy-resin surfboards by the thousands. That stuff just won’t break down," he said. "And after working with traditional board-making for the last 20 years, man, we just don’t want to breathe the fumes or sand that dust anymore. Nasty and toxic. Can’t we just repair and reuse older boards? And why doesn’t everyone?"

To alter that disposable-surfboard mindset, Goo realized that recycled boards should have a green cachet. The answer was to re-cover the board in a different material, even if it slightly roughened the surface.

And so — bark.

"We began looking into it, and tree bark is amazing material, very tough. I was taking a walk and the tree-trimmers were showering this stuff down, and I began looking at it, and thinking, ‘Whoa, can this be used?’ I took home a whole bag of bark."

Although American Indians built birch-bark canoes, Goo discovered the material needs to be tweaked before it’s usable. Basically, it needs to be boiled and pummeled until it’s flexible enough.

"And then we stick it into place with waterproof, earth-friendly glues, not resins. Nobody in our shop has to wear a mask! Can you imagine?"

It’s pretty difficult to imagine a surfboard shop without masks — and without reeking of chemical fumes or neighbors with headaches. Goo said some of his guys wear a mask anyway. They can’t help themselves.

A good source of well-battered boards is Salty’s Surf Shack at the corner of Iolani and Queen Emma streets. "The guys there, Jake Casarez and Marcelo Palacios, are totally into recycling and dig what we’re doing. They’re living their dream by giving old boards new life," said Goo.

Instead of chemical resins, Goo is experimenting with an age-old material, shellac. "The R&D guy at TiteBond Glue actually steered me that way," he said. "Old-fashioned shellac is amazing stuff. It’s exuded by the lac beetle, collected and boiled, then poured into sheets, dried and shattered into flakes. It’s only soluble in alcohol. It’s been used for centuries on fishing rods and boats. Why not surfboards?"

Shellac and bark are both naturally grown materials, unlike resin and glass cloth, and actually cheaper to use.

The bark-covered boards used in Bishop Museum’s exhibit are the same boards he’s recycling for surf-simulator rides. Despite hundreds of people jumping on these land-based boards during conventions and trade shows, Goo said they actually hold up pretty well.

"People love Hawaii and they’re respectful of surfing, and so the sim boards come back in good shape. Every time you see a picture of someone trying it out at a convention, they always have a big smile on their face."

Goo is serious about surfboard-simming. His sim boards have air bladders and motion sensors to emulate the slippery footing real surfing entails. "You see surf instructors, all the time, just put a surfboard down on the sand and put the student on it. Doesn’t feel right."

Naturally — and that word has never been more right — Goo is looking for recycled, green replacements for his sim components. Coconut-shell halves are replacing the rubber bladders; laptops that would normally be tossed in the dump have a second life as game controllers.

Their progress in greeny surf tech can be tracked at www.ecosurftech.com, and Goo, while designing computer games that stealthily teach eco-knowledge to kids, has learned perhaps more than he wants to about ocean pollution.

"You know what one of the worst things is? Cigarette butts. Man, they don’t decompose, they’re full of arsenic and nicotine and tar, and fish eat them — and fishermen are always flicking their butts into the ocean."

Ironically, as Goo completed his first recycled bark-board, someone wanted to buy it and hang it on the wall as artwork. Look at the details: The kapa design around the rails is made of bark strips and charcoal mixed with glue. The source for the charcoal was abandoned picnic barbecues at beach parks.

What about the dings in boards? Is there a natural substance that will fill the dents?

"Rice."

Rice?

"Oh yeah. Boil up some rice, moosh it in, let it dry. Hardest substance known to man. That’s why your mom always made you wash rice off your plate right away."