Whale watchers turned wildlife warriors this afternoon as passengers on board a whale-watching boat attempted to free a 10-metre humpback tangled in nets off Bondi Beach.

The crew of the Whale Watching Sydney vessel, Ocean Dreaming II, contacted the NSW National Parks and Wildlife Service after finding the distressed animal, injured and bleeding, at around 2pm, the Sydney Morning Herald reports.

“It was moving slowly, looked exhausted, and as the boat got closer we could see it had ropes wrapped around its tail and its pectoral fin and head," Jonas Liebschner from Whale Watching Sydney told SMH.

NSW National Parks and Wildlife Service dispatched a helicopter and boat to assess the situation, but had to call off the rescue until tomorrow morning due to failing light.

The whale has not been without help, though, and crew of the Ocean Dreaming II took matters into their own hands, managing to cut come of the netting and ropes trapping the whale, and increase its movement.

“It will be dark in a couple of hours and if you lose the whale to the darkness you won’t find it again and it could die,” Liebschner told SMH. “Hopefully this is a hero story in the making.”

It’s unknown how the whale become entangled, and exactly where the suspected fishing lines came from, but it’s likely the it will remain trapped overnight.

The NSW National Parks and Wildlife Service helicopter located the whale, noting the pace of its movement north, and the service will resume its efforts tomorrow, assuming the whale can be found. According to Whale Watching Sydney, about 20,000 humpback whales will migrate north along the NSW coast from Antarctica to warmer waters off north Queensland between May and August this year.