Irons was only 32 and leaves behind a pregnant wife, Lyndie, and younger brother, Bruce, who is a former World Tour competitor.
Irons passed away in a Dallas hotel room during a layover between flights from Puerto Rico to his home in Hawaii. He checked into the hotel Monday and his body was discovered Tuesday morning, after he failed to respond to a wake-up call.
Though Irons was said to have contracted dengue fever, investigators found a prescription bottle of Alprazolam (Xanex) and a prescription bottle of Ambien in his hotel room, and are investigating the cause of death.
An autopsy Wednesday is expected to reveal the cause of death.
A statement from Irons' family begins: "The world of surfing mourns an incredibly sad loss today with the news that Hawaii's Andy Irons has died. Andy was a beloved husband, and a true champion."
Irons, who was born and raised on Kauai, pulled out of the Rip Curl Search Puerto Rico on Sunday, citing an illness he contracted during the previous contest in Portugal.
He was known for his fast but fluid style on a surfboard, and for his epic heat battles with Kelly Slater, many of which occurred as Irons was reeling off his titles in succession from 2002-04.
Irons also was a dominant force in Hawaii, where he won four prestigious Vans Triple Crown of Surfing titles and four Billabong Pipeline Masters championships.
The Triple Crown is scheduled to begin next week. Event spokeswoman Jodi Wilmott told the AP: "The thing that I think many of us appreciated the most about Andy was that he was an incredibly real person. 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."
Billabong, Irons' primary sponsor, posted a tribute page on its website, which includes this statement: "Andy was 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."
Lyndie is scheduled to give birth to the couple's first child, a son, in December.
Irons' death comes at a time when Slater, 38, pro surfing's most accomplished athlete, is in Puerto Rico trying to clinch a tenth world title. Slater was shocked and saddened by the news, telling the press that Irons made him better.
Irons had his ups and downs after his title run and often struggled with his surfing and emotions. He took last year off, citing personal reasons, but being newly married seemed to provide him with new inspiration. He returned to the tour this season and is presently ranked No. 16 in the world.
Photos: ASP/Via Kirstin
Related: Surfers to the rescue in the Mentawais.
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