California authorities on Saturday launched a major operation to rescue a humpback whale that swam into the Southern California harbour and got trapped there. Spectators flocked to see the rare sight while Coast Guard, the National Parks Service and local authorities collaborated to free the 40-foot-long mammal, AP reported.

Ventura Harbor Patrol Officer Tim Burrows said the whale was not injured, Los Angeles Times reported.

Officials say the whale was spotted swimming back and forth in the area. Stranding operations and animal care manager for the Channel Islands Marine and Wildlife Institute says rescue operations will involve using a hydrophone to release underwater whale sounds to guide the whale out of the harbour, AP reported. A wildlife expert said the mammal was a healthy juvenile.