PORT STEPHENS, Australia (AP) 鈥 The ferry was late, but not because of the usual traffic. Sydney commuters watched from an idling boat this month as humpback whales the size of buses surfaced nearby, halting the vessel鈥檚 passage across the harbor. The curious mammals seemed to be watching them back.

In June and July, it鈥檚 not uncommon for whales to stop water traffic in Sydney. Winter heralds the opening of the so-called humpback highway, a migratory corridor along Australia's east coast used by about 40,000 of the massive creatures as they travel from feeding grounds in freezing Antarctica to tropical breeding areas off Queensland state.

鈥淚t鈥檚 blubber to blubber,鈥 said Dr. Vanessa Pirotta, a wildlife scientist at Macquarie University in Sydney and author of the book 鈥淗umpback Highway.鈥 During peak traffic periods the bustling coastal city of 5.5 million people becomes one of the world鈥檚 few urban centers where you might see a breaching whale on your morning walk, while buying a coffee, or waiting at a bus stop 鈥 anyplace you can see the ocean.

Whales cruise close to shore

The reason humpbacks on the highway are so visible is due to their size 鈥 adults can be 16-17 meters (52-56 feet) in length, and weigh 40 tonnes 鈥 and their proximity to people. On their 10,000km (6,000 mile) journey from icy to balmy waters, one of the world鈥檚 longest mammal migrations, the creatures stay close to shore.

鈥淭hey are incredibly curious,鈥 said Pirotta. 鈥淭here鈥檚 been times where there鈥檚 been whales in the harbor this year where they鈥檝e literally halted traffic.鈥

Australians get so close to the creatures that some have attracted fans. Among them are Migaloo, an all-white humpback whose sightings spanned 1991 to 2020, and Blade Runner, named for her tussle with a boat propeller that created her long, distinctive scars.

Humpbacks go people-watching

Some keen whale watchers seek a closer look. On a recent morning, Ben Armstrong, a veteran skipper of a whale-watching boat in Port Stephens, a scenic harbor north of Sydney, slowed the engine as two humpbacks breached nearby.

He encouraged passengers to put down their phones and enjoy the spectacle. Armstrong keeps his tourist boat at distances mandated by Australia鈥檚 state laws, but inquisitive whales .

Once, the skipper let his boat drift for an hour while four or five humpbacks treated the vessel 鈥渓ike a bath toy," playfully preventing it from moving forward or back. In another episode, a whale peeled away from its pod and rushed to the boat, 鈥渓ike a dog greeting its master at the gate,鈥 he said.

It lounged for 40 minutes in the water, rubbing its massive fins against the vessel. 鈥淚t was like, 鈥橭h, there鈥檚 that boat I really like,鈥 said Armstrong.

Vincent Kelly, who travelled from Geelong, Victoria, to witness the migration was a recent passenger. Over two hours, he watched half a dozen humpbacks perform breathtaking aerial maneuvers.

鈥淚t was unbelievable to me,鈥 Kelly said. 鈥淚 didn鈥檛 expect to actually see a whale. But they were everywhere.鈥

The congestion marks a conservation comeback

The humpback gridlock marks a sharp reversal of fortune for the whales. They were once hunted for meat and oil, and numbers dwindled to a few hundred before humpbacks became a protected species in the Southern Hemisphere in 1963.

The humpback boom to about 40,000 since has brought the creatures into more frequent contact with people than before. That means more entanglements with fishing nets or run-ins with watercraft.

Where and when they appear has become less predictable too, with whales in recent years giving birth to calves the size of small cars in unexpected places. Harvesting of krill, which humpbacks eat in bulk, and heating seas due to climate change could be altering their migratory patterns, Pirotta said.

The population is still growing steadily, amplifying concerns about how humans and giants of the sea can safely share the coastline. But it also puts millions of Australians a short walk and a little luck away from encountering one of the largest mammals on the planet.

鈥淚t grounds you, I think,鈥 said Armstrong, the boat skipper. 鈥淚t makes you realize there鈥檚 a lot more out there than what we think there is in nature.鈥

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