Red jellyfish swarms are an annual occurrence in parts of Western Australia. But a pair of local surfers who went out into the waters on April 8 off Exmouth say they’ve never seen one of this scale before.

Riley Watts, 18, and his friend were planning on surfing but changed their minds when they noticed hundreds of thousands of red bell jellyfish in the ocean. They then took their boat out to get a closer look.

Watts, who has lived in Exmouth his entire life, told ABC North West: "We were just heading out for a surf, got about halfway out and there were frickin’ jellyfish everywhere, so we turned around and went home.

“The whole west side of Exmouth was just packed with them, all the way from the national park to the point basically… just kilometres and kilometres of them.”

While not as deadly as the Irukandji jellyfish, whose sting can be fatal, contact with a red bell jellyfish can still be painful.

Watts told Storyful he went surfing at what he believed was a clear part of the ocean, only to get “absolutely nailed” by the jellyfish anyway. Watts said they were still in the waters at time of writing. Credit: Riley Watts via Storyful