On July 4, Mark Bender will return to Hawaii for the first time since the accident that changed his life three years ago: While swimming at Waimea Bay in March 2013, he was thrown by the shorebreak and was paralyzed from his chest down.

“We were celebrating our 15th wedding anniversary. It was the last day of our trip,” Bender said by phone from Washington state, where he lives with his wife, Sarah, and their four sons.

Determined to remain active despite being confined to a wheelchair, Bender, 41, said the reason for his trip is to return to the waters of Waimea Bay. Thanks to a WSUP, he’ll get his chance.

In the expected calm conditions that are the norm during North Shore summers, Bender will be paddled offshore on a new stand-up paddleboard with a wheelchair and outriggers. “It was on my bucket list to get back there,” he said, his voice sounding hale and vigorous above the background noise of his children playing.

The WSUP was designed and manufactured by Honolulu City and County lifeguard Kainoa McGee and Amundson Customs, a water sports shop in Haleiwa.

“The WSUP is a versatile, adaptive board we developed to give people with physical, mental or emotional disabilities the feeling of freedom and independence on the water,” said McGee, a 44-year-old champion stand-up paddleboarder and bodyboarder.

McGee produced a prototype WSUP this year in partnership with local surfer Kawika Watts, who created the first adaptive ability board, and Amy Lagera, a California businesswoman. The prototype is 12 feet 6 inches long, 34 inches wide and 6 inches thick. The outriggers provide stability.

“It can hold up to 600 pounds,” he said. “It’s so buoyant that it floats and glides really well.”

The prototype demonstrated its stability and appeal in a paddle around the Ala Wai Small Boat Harbor on June 6. Samantha Spencer, a disabled child from Utah with several life-threatening medical conditions, rode in the WSUP’s special wheelchair, accompanied, in rotating shifts, by her parents, three sisters, Lagera and McGee.

The Spencers were visiting Oahu with the support of Make-A-Wish Hawaii.

“Her mom said Samantha had been in a bad mood — she said you can tell when her arms are up,” McGee said. “As she rode on the WSUP, Samantha’s arms dropped to her sides, and she started looking around, looking up at me. Her mom said she was relaxed.”

McGee said he can relate to disabled people’s yearning for freedom of movement after having been in the hospital with a coma following a seizure in 1999. Although he never received a final diagnosis, his doctor’s “best guess” was viral encephalitis, which kills 50 percent of those who get it and paralyzes 40 percent, he said.

With the goal of getting more wheelchair-bound folks out on the water, McGee founded the Adaptive Freedom Foundation, a nonprofit organization that is trying to raise money to build more WSUPs and make them widely available.

The WSUP will be launched July 4 at Da Hui o He‘e Nalu Independence Day Paddleboard & Stand Up Paddle Race at Waimea Bay. Sammy Sampaga, who has muscular dystrophy, plans to travel from Hilo to paddle the WSUP in the race.

“It’s amazing,” said Sampaga, 44, of his practice runs on the paddleboard. “You paddle sitting in the wheelchair. It doesn’t have arms, so you can really reach out and grab the water, like in a canoe.”

To help pay for travel costs for Spencer, Sampaga and their families, and further its mission of developing and producing more adaptive ability WSUPs and “getting more people out on the water enjoying life,” McGee said, the Adaptive Freedom Foundation is seeking donations at gofundme.com/adaptivefreedom.