A whale has been spotted in Sydney Harbour, halting ferries and putting on a show for tourists.

The humpback whale dazzled tourists and locals in Circular Quay this morning, with ferries halting operations momentarily.

Meanwhile, NSW maritime crews sailed alongside the whale to escort it back out to sea.

Dr Vanessa Pirotta, a marine scientist working with NSW Maritime, confirmed the sighting on her social media accounts. 

She said a whale in the harbour is beautiful to see, it poses a “navigational nightmare” for passing boats.

The New South Wales Water Police, along with the Port Authority and Transport for NSW, advised all vessels in the harbor to be vigilant for the whale and to maintain a safe distance as it was guided back to open waters.

The humpback is one of 40,000 migrating to Queensland to mate and give birth.

The whales embark on an annual 10,000-kilometer trek, beginning from Australia’s east coast in April and concluding near the warm shores of Queensland by November, reports the Department of the Environment and Water Resources.

During migration months, whale sightings off the NSW coast are common, such as a pair seen breaching near Lennox Head earlier this month.