The male winner won R8,000 (just over NZ$800) while the female winner won exactly half, for doing the exact same thing.
People took to Facebook to express their disappointment.
"Wow! Blatant inequality Billabong ... I hope your clothes are half the price for women if this is the case," a Facebook user commented.
"Did the girls surf a different ocean that was easier we don't know about ? This is pathetic," another one said.
"I'm sorry but this is actually disgusting. I am outraged. I was there and watched the whole day, these girls shred just as hard as any boy," someone else commented.
Faced with the waves of criticism, the organisers later put out a statement on social media, shifting the blame to someone else.
"The World Surf League is the governing and sanctioning body of the event that determine all prize money and rankings. We have brought this to their attention for further comment," the tournament organisers said.