From April to mid August the Humpbacks are heading north to give birth and mate in the waters of the Coral Sea.
This current is usually found only within 3 nautical miles (5.6 km) of the coast, so most of the migrating population will pass within this distance.
This is the easiest time for shore based spotters to see the full population of humpback whales passing by the Sydney coast as they head north.
Often on the Northern migration, especially when the currents are strong close to shore, a Humpback pod may enter the harbour for a short time.
At this time they generally swim slower than on the northern migration and use the East Australian Current to move them south.
However, during Early October to Mid December the mothers and newborn calves pass south, they tend to swim very close to the shoreline.
Sperm whales are present off the coast of Sydney but tend to stay near the edge of the continental shelf over 20 nautical miles (37 km) to sea, so are not often seen close to shore.