Hawaii is known for its blue skies, warm water and young people thrilled to be catching their first real waves.
What these enthusiastic beginners might not know, and what few people realize, is that a mysterious threat could be lurking not under the water but in their bodies.
Joe Guintu of Los Angeles and his girlfriend Ivette Flores took a trip last year to Hawaii, where Guintu decided to take a surfing lesson. After some brief instruction on the beach, he was in the water and managed to catch a wave almost immediately.
But something wasn't right. By the end of the lesson, Guintu said, "everything just seemed off."
As Guintu, 25, got out of the water and headed toward some stairs to return his board, he thought, "This is impossible."
He couldn't climb those stairs -- he couldn't even walk. His legs had given out.
An ambulance rushed him to Straub Hospital in Honolulu. Flores remembered asking medical assistants and nurses, "Have you heard of this, do you know what it is?"
No one seemed to have an answer.
But neurologist Beau Nakamoto had seen cases like this one before. By the time Guintu reached the hospital, Nakamoto said, he was essentially paralyzed from the waist down. The doctor immediately suspected surfer's myelopathy.
"Visitor from Hawaii goes surfing for the first time, develops low back pain, comes out of the water, feels that their legs are weak, can't urinate," Nakamoto said. "And then over the next hour or so, have varying degrees of weakness. The story is always the same."
Nakamoto sees two or three new cases of surfer's myelopathy each year. But most first-time surfers -- and even most surfing instructors -- have never heard of this rare complication and have no idea what the warning signs are.
Mike Fritschner was on the lookout for waves, not lower back pain, when he hopped on a board in the summer of 2006. The Fritschners were taking a Hawaiian cruise and 15-year-old Mike, a natural athlete, was eager to try surfing.
Twenty minutes into his lesson, the Bell Canyon, Calif. teen stood up on the board and felt what he describes as "a little pop in my back ... almost like a morning stretch." Unconcerned, he paddled out to catch another wave, but soon felt a pain in his spine that became first distracting, then unbearable.
Fritschner and his surf instructor both thought the pain was normal, a result of working new muscles. But soon he, like Guintu, was unable to feel his own legs.
Unlike most sports injuries, surfer's myelopathy is not the result of an obvious accident or trauma. Instead, it seems to be a mechanical problem that starts in the blood vessels surrounding the spine.
Dr. James Pearce is the man who first documented the condition nearly 25 years ago.
When the spinal cord is hyperextended -- as when a surfer arches his back on the board -- it can interrupt the blood flow to the spine, he explained. One theory holds that frequent repetition of this motion causes a kink in the blood vessel, much like kinking a garden hose. The spinal cord is starved of oxygen, something Pearce calls a "stroke to the spine."
For now, there is no medication or surgery to treat surfer's myelopathy. Many patients do recover, however, a goal both Guintu and Fritschner are working hard to accomplish through intense physical therapy.