A 35ft humpback whale has been trapped in a California harbour, with marine experts flocking to help it escape back into the ocean.

Large crowds gathered to see the whale, which is believed to be an adolescent, after it had journeyed into Ventura Harbour, east of Santa Barbara.

It is thought the whale arrived in the harbour at around 6pm PDT (1am GMT) before swimming around under boats for hours before authorities arrived to deal with the situation.

The whale is being helped by the US Coast Guard, National Parks Service and local authorities. Four rescue boats have been used to tempt it back into open water.

One plan to help rescue the creature involves playing familiar whale sounds and recordings in the hope it might try to find members of its fellow species.

Habour master John Higgins said the animal had sustained "superficial" injuries after crashing into boats while attempting to make its way through boats.

He said: "I know that earlier today when it was navigating... under the lower tide that it was bumping into boats and there was some superficial cuts and bruises to it, but I don't know to what extent."

Spectators that had arrived on the scene to catch a glimpse at the whale had mixed emotions – some were excited to see it up close and others were saddened at the whale being lost and trapped.

One witness said: "It's amazing, absolutely amazing," a witness said. "I've never seen a whale this close up before."

However, another was more concerned for its welfare, stating: "It's heartbreaking to see the whale lost and turned around. It's beautiful to see so close but sad circumstances."