Just two baby southern right whales have been seen in NSW waters this season and both are making their way along the Illawarra's coast within days of each other.
But while the rare sightings are exciting, people are urged to keep their distance and let the mothers and their new babies rest and feed without disturbance.
One calf and its mother have been heading north and were last seen off Shellharbour on the afternoon of Saturday, August 19.
Another mother-and-calf pair of the endangered species, travelling south, was spotted off Little Bay in Sydney on Sunday morning.
Jessica Fox, secretary for the Organisation for the Rescue and Research of Cetaceans in Australia (ORRCA), said the latter pair was likely to come past Wollongong on Monday.
"It's incredible to get to sight them, let alone two pairs in a week," Ms Fox said.
The calves are the only two southern right whale babies seen in NSW waters this season while their mothers are among just six adults spotted.
The National Parks and Wildlife Service has tracked the southbound mother and calf since July 27, when they were first spotted together off Coffs Harbour.
ORRCA says the mother was first seen off Bermagui on July 15.
The other pair, last seen off Shellharbour, was first spotted off Batemans Bay in mid-August.
The sightings of the whales have prompted reminders that people must keep their distance to avoid stressing the animals.
ORRCA says the southbound mother-and-calf pair moved on from Avoca Beach on the Central Coast after being crowded by swimmers and surfers.
A legally enforceable exclusion zone of 300 metres applies for anyone on the water, swimmers and divers cannot come within 30 metres, while drones cannot come within 100 metres nor hover above them.
A calf aged three to four weeks, like the one heading south, needs to nurse and consume about 300 litres of milk each day for the long and dangerous trip back to Antarctic waters.
"Approaching the pair in a boat, with a drone or on a jet ski, kayak or surfboard not only compromises a calf's ability to nurse and get the sustenance it needs to grow, but it can also drive the whales away from their shallow resting places and out into deeper waters, where they are exposed to predation by orcas and sharks," NPWS marine wildlife team member Andy Marshall said.
Unlike humpback whales, which travel north to Queensland to give birth, southern right whales migrate from Antarctica to breed and give birth in and around NSW's coastal bays from about May to October.
ORRCA is helping NPWS to identify and track southern right whales under a government research project called Right Whale ID, which aims to better understand the whales' movements and improve protections for the species.
There are less than 270 animals in the south-east Australian population of southern right whales after the species was almost hunted to extinction.
Anyone who sees a southern right whale is urged to call the NPWS on 13000PARKS or ORRCA on 9415 3333.
Southern right whales have a mostly black body with white patches on their head and lower jaw; they also lack a dorsal fin.
Meanwhile, ORRCA has received concerned calls about a humpback whale off Bass Point, but it is not in any distress.
Ms Fox explained whales sometimes slowed to have a rest or feed.
Sign up for our newsletter to stay up to date.