Imagine being on a mo-ped — helmet on, hands poised on the throttle, ready for the rush that comes with cruising in the open air. Total freedom! Total exhilaration!

Now think about doing that underwater. Island Water Sports Hawaii offers guests the chance to zip around Maunalua Bay, on Oahu’s southeastern shore, in battery-powered submersible scooters.

"It’s just like riding a mo-ped," said Sam Montgomery, owner of Island Water Sports Hawaii. "You sit on a comfortable seat with your head in an acrylic dome-shaped headpiece that’s constantly pumped with oxygen, so you breathe as you normally would without the constraints of conventional dive equipment. There’s enough room in the dome for you to reach up and put on your prescription glasses, make a ‘shaka’ sign and scratch your nose if you have an itch."

The headpiece operates on the same principle as that elementary school science experiment where a paper towel is crumpled into a ball and pushed into the bottom of a glass. The glass is then placed upside-down into a bucket filled with water. Slowly lift the glass out of the water, being careful to keep it vertical. Amazingly, you’ll find the paper towel inside it has remained dry.

"That’s because the glass was already filled with air and the paper towel before it was put in the water," Montgomery said. "When the glass is submerged upside down, the air can’t escape, and because air takes up space, water can’t get into the glass. The air prevents the water from entering and wetting the paper towel."

According to Montgomery, the headpiece provides better peripheral vision than a dive mask, and because it’s connected to the scooter, tour participants don’t have to support its weight. In fact, no special gear is required — no confining wet suit, buoyancy compensation vest, weight belt, regulator, oxygen tank, hood, gloves, boots or fins.

Steering<$o($)> the scooter just as they would a bike, riders can venture up to 150 feet in all directions from Island Water Sports Hawaii’s 40-foot dive boat. A tether attaches each scooter to a buoy, setting the depth at 8 feet. Riders glide at about 3 miles per hour amid triggerfish, angelfish, Moorish idols, yellow butterfly fish, white butterfly fish, turtles, eels and other intriguing marine life.

"The scooters are safe, fun, comfortable, eco-friendly, easy to operate, and you don’t have to have prior snorkeling or scuba experience," Montgomery said. "Even nonswimmers can do this activity; they just have to be able to put their head in the water about a foot and a half. For added peace of mind, each person is accompanied by a dive master, regardless of his or her age and ability in the water."

Montgomery discovered the scooters while vacationing with friends in the Caribbean a few years ago. "We had a blast, and I thought the scooters would be a perfect fit here," he said. "I contacted the manufacturer, and he gave me an exclusive for Hawaii, meaning we’re the only company in the state that has them. We started our scooter tours in January, and it’s great to see our guests coming out of the water with big smiles on their faces. The comment we hear most often is, ‘Wow! That was amazing!’"

Island Water Sports has four scooters, with more on the way. "The appeal of this activity is when you’re on the scooter, you’re the captain," Montgomery said. "There’s something really cool about being in control of your own self-propelled electric eco-friendly submersible scooter and being face to face with incredible marine life. It’s the ultimate water toy!"

Cheryl Chee Tsutsumi is a Honolulu-based freelance writer whose travel features for the Star-Advertiser have won multiple Society of American Travel Writers awards.