LITTLE COMPTON— He kept up a good front in the Hawaii hospital, joking with friends about the big tiger shark that had taken his leg during an Oct. 9, 2015, surfing adventure off Oahu’s Leftovers Beach. There’s even a photo of 25-year-old Colin Cook lying there with the jaws of a stuffed animal shark clamped around the bandaged stump of his left leg.

But when visitors were gone for the night, there were low moments, plenty of them, he says.

“Everybody tells you you’ll be back up soon, right back at it,” he said. “But you don’t have any idea what is coming.”

“And my first concern was, ‘how am I going to surf again?’” Colin said.

“I grew up surfing,” mostly off Little Compton — surfing and building surfboards was what drew him to Hawaii. “Everything revolved around surfing. It was what I loved to do, it was my life.”

That life suddenly seemed distant. Only three people who’ve lost legs above the knee have managed to surf standing up.

“It was a month before they could even try to fit me with a prosthetic leg and, when they did, the pain was terrible.”

A subsequent version, affixed with suction, was much more comfortable, and back at his family’s Seapowet home he began learning to walk again — the leg remained tender and sore but improved steadily. Like many who’ve lost limbs, he still feels the leg and foot that are now gone. “It’s very real — some mornings it takes a moment to remember that the foot I feel isn’t really there.”

Fourth at Worlds

Turns out those friends who assured him he’d be back out there someday knew Colin well — even they, though, couldn’t have imagined how quickly he’d return to the waves.

In early December, just over a year after the attack, Colin was not only back surfing, he was standing on the medals platform in San Diego at the International Surfing Association’s World Adaptive Surfing Championship.

Among 77 contestants from 23 countries he’d worked his way up through two days of heats to a fourth place finish. And of those ahead of them, only one surfer, Eric Dargent of France, had lost a leg above the knee (also to a shark). “A great guy — everybody out there was wonderful.”

He too had had a custom surfing prosthetic built. “Ours are different, every situation is different, but it was really interesting to compare them.”

His surfing goal now is to compete in the Paralympics.

Colin credits the support of family and good friends with his remarkable comeback.

Had he lost his leg below the knee, there would have been lots of prosthetic surfing options.

“Above the knee, though, there’s nothing out there. The knee is such a critical joint for surfing, for everything.” So much of the balance, steering of the board is controlled at the knee.

“But I got some ideas in my head about how it might be done, kept working them over and over, what it might look like.”

Some among his Sakonnet surfing friends have fertile imaginations too — and serious carbon fiber talent.

Max Kramers (Portsmouth Abbey grad) and Brendan Prior were part of the young team that designed and built Scout, the solar powered autonomous transatlantic boat. The 12.8-foot carbon fiber boat departed Sakonnet Point in 2013 and was well on its way to a programmed destination of Spain before it vanished. (They are now working on a second try.)

Brendan now operates Waterman Marine in Bristol, where Colin also works, and helping get their friend back out on a surfboard became an obsession.

The challenge was to create something that could flex at the knee and ankle yet be stiff enough to provide support and the push needed for control.

And “I needed to be able to feel the board and have good grip.”

There’ve been several versions, each improving something that wasn’t quite right with the predecessor. Foam nonskid was added to the sole of the foot, the bowed carbon limb was shortened, the foot was angled out a bit …

“It felt pretty awkward at first — I really felt like I had almost no contact or control.” But “almost right away it started feeling better and better — it’s amazing now.”

In the meantime Colin trained relentlessly — jumping rope, balancing on rollers, rebuilding his strength and endurance.

Colin said his surfing is nowhere near back to what it was, “but I’m getting there.” He said he feels in control of the board, can steer and cut back … “every time out it feels more natural.”

As before, Colin surfs every chance he gets — a Facebook post shows him by the Little Compton shore with snowflakes flying in the midst of the recent storm. Last Thursday, among a handful of surfers at a windy South Shore Beach in Little Compton, he managed many of the morning’s longest rides.

Dating a Boston survivor

He rides mostly in Rhode Island but has been back to Hawaii. There, he cage dove with sharks and had a reunion with Hawaiian surfer Keoni Bowthorpe. It was Keoni who paddled his board to Colin’s rescue, fending off the shark and towing the bleeding surfer to shore while the 10 to 12-foot shark continued to circle. A Hawaiian newspaper ran a photo of the two titled “Blood brothers.”

“A major hero, Colin says of his friend. “I would not be here without him, no doubt.”

Colin said he does not fear sharks nor does he bear them any ill will.

“When I go surfing I am entering their world,” he said, adding that he is appalled by the global massacre of sharks.

Out of the water, Colin is dating a survivor of the Boston Marathon bombing and, through her, has met many of the survivors.

Their resolve to get back to doing things they enjoy has been inspirational and helps fuel his determination to improve his surfing and build an ever-better prosthetic limb.

“We’ve made so much progress in such a short time and I know we can make it even better. We’re getting there.”