The roughly 40-foot-long ‘healthy juvenile’ is swimming back and forth in the waters.

A humpback whale swam into a Southern California harbour and got stuck there, drawing spectators and news helicopters as boat crews try to guide it out to the open water.

Ventura Harbor Patrol officials say the whale was spotted on Saturday afternoon and has been swimming back and forth in the harbour.

Whale sounds to guide it out

A wildlife expert said the approximately 40-foot-long whale appeared to be a healthy juvenile. Jen Levine, the stranding operations and animal care manager for the Channel Islands Marine and Wildlife Institute, says rescuers plan to use a hydrophone that plays underwater whale sounds to guide the whale out of the harbor.

The Coast Guard, the National Parks Service and local authorities are involved in the effort.