World surfing champion Kelly Slater says Bali's beaches are littered with the "worst pollution" he has ever seen.
Slater, who has won 11 Association of Surfing Professionals world championships, voiced his concerns on popular micro-blogging website Twitter on Sunday (Melbourne time) from Bali.
"If Bali doesn't #DoSomething serious about this pollution it'll be impossible to surf here in a few years. Worst I've ever seen," he told his hundreds of thousands of followers.
When asked by a fan to elaborate on the source of the pollution, he tweeted: "Everything. Plastic, random rubbish, medical waste/needles on beach. Disgusting. Smelly water. Really sad."
He said solutions to the problem would require support from multiple industries.
Slater later re-published — but did not respond to — a follower's suggestion he make a documentary to prompt the Indonesian government to examine the problem.
Bali was ranked third on CNN's list of 50 best surfing spots — after Hawaii and Jeffrey's Bay — in the world earlier this year.
"The island attracts the gnarliest surfers from Australia and Hawaii plus beginners from across the globe; all of whom can enjoy these perfect glassy faces," CNN reporter Jade Bremner said.