Phil Irons, the surfer's father, confirmed his 32-year-old son's death Tuesday. The cause was not immediately known. Andy Irons' wife, Lyndie, is expecting the couple's first child in December.
Irons was found dead Tuesday morning in a hotel room in the Dallas area during a layover en route to his home on Kauai. He was returning from Puerto Rico, where he was to compete in the 2010 Rip Curl Pro Search. He withdrew citing an illness he contracted in Portugal.
The Tarrant County Medical Examiner was performing an autopsy Wednesday to determine the cause of death.
Irons claimed the world championship in 2002, '03 and '04, and was a four-time winner of the prestigious Vans Triple Crown of Surfing. He was well known in the surfing world for his rivalry with nine-time world champion Kelly Slater.
Irons was revered on his home island of Kauai, along with his younger brother Bruce, also a pro surfer. Irons was raised and learned to surf on the North Shore, where he was married three years ago.
Billabong, one of his sponsors, had a tribute on its website, calling Irons one of the "greatest surfers of our time."
"More than that, he was a much loved son, a devoted husband and a soon-to-be father. The thoughts of all Billabong employees worldwide are with wife Lyndie and Andy's family at this most devastating time," the company said.
Irons' wife is scheduled to give birth to a son next month.
The tribute page includes a video clip of Irons talking about making a comeback and fighting "inner demons."
Employees at the Grand Hyatt Hotel DFW Airport found the body and called Dallas-Fort Worth International Airport police at 9:44 a.m. Tuesday. Public Safety officials said the guest had checked in Monday and had died of unknown causes.
Irons was expected to compete against two Australian surfers in his first heat Saturday in Puerto Rico, but didn't show up. Rip Curl officials announced his withdrawal Sunday.
Irons was scheduled to compete in the 2010 Vans event, which begins next week in Hawaii.
"The thing that I think many of us appreciated the most about Andy was that he was an incredibly real person," Triple Crown spokeswoman Jodi Wilmott said. "Where a lot of champions in sports and celebrities become very guarded and you just wonder sometimes if you're really seeing who they are, you've got Andy Irons 100 percent of the time."
Wilmott said Irons was a passionate person and an incredibly competitive athlete.
"He reveled in competition and in stepping up to the plate and I think that's something in sport that anybody can admire," she said.
The Billabong website also had a video of Irons talking about the first wave he ever caught.
"I thought right then, 'This is the coolest thing in the world.' ... I literally will never forget that wave," Irons said.
Irons' family released a statement thanking the surfer's friends and fans and requesting privacy "so their focus can remain on one another during this time of profound loss."