They form two perfect arcs as they dive, then reappear, slap their "arms" on the water as if it's the most hilarious thing ever, and do a sort of side-stroke, synchronised-swimming style. Then they disappear in the depths again, seemingly in the knowledge that suspense is everything.
As minutes tick by the tension is unbearable. Where will they surface next?
A shout of "at 3 o'clock" and a couple of dozen heads turn as one: there is after all, only one show in town on this sparkling Sydney afternoon.
We are being entertained by the antics of two whales off Sydney's southern beaches and far from flinching at the two whale watching boats and a smaller craft holding a dozen divers, these two trouper humpbacks seem to be going all out to impress their audience.
We have reached that point in this whale watching expedition when the question has to be asked: just who is doing the watching?
The two whales are regulars, one is rather prosaically named Tony (is there something we don't know here – should there be a Soprano attached to it?) and the other the more self-explanatory Cheeky.
Just when we think their 15-minute show must be over they reappear. It is clear these two have a touch of the Nellie Melbas about them and seem to never tire of slapping the water with their fins. Our guide says there are various opinions about what the slapping means: it could be a means of shedding skin or barnacles; a method of communication; a form of play – or, it could just be for the hell of it. In any case it's very reminiscent of a drunken reveller backslapping his mates after telling a few jokes. We are on the Nancy Wake, one of two Captain Cook Cruises' ocean-going catamarans that take advantage of Sydney's show-stopping whale migration spectacle, each May to November.
So numerous are the whale numbers during the season and so confident are the operators about seeing them, that all paying guests are offered a free trip if a whale is not sighted.
The suspense that builds as all eyes are peeled for that first sighting is all part of the fun on a whale-watching cruise. A hush falls over the boat as we pass the Heads and the city skyline drops away. Where are they? There's a cry as we encounter a pod of dolphins who spin and play in the wake of our rocketing craft. Later we spot our first whale splashes in the waters off Coogee.
The fact that you can watch humpbacks doing what they do so close to a major city is something the overseas visitors on our boat marvel at. One way to further enhance the experience, particularly for families, is to enjoy a double whammy of sea life. A special pass now enables you to visit The Sea Life Aquarium at Darling Harbour in the morning and then jump on a one-way rocket ferry to Circular Quay to go whale watching in the afternoon.
The aquarium is a great precursor to the afternoon cruise, adding perspective and whetting appetites to see whales in the wild. However the pre-paid queue is long and slow-moving when we visit, and it takes us a good half-an-hour to get in the door which cuts short our time at the aquarium.
What we do see, however, is more than worth our while: playful king penguins, gentoo penguins and little penguins are a highlight. Later, multi-coloured fish and turtles fly by as we wander through more than 100 metres of glass viewing panels as smiley stingrays and zig-zagging sharks cruise over our heads.
Jane Richards was a guest of Captain Cook Cruises and the Sea Life Aquarium.
The Sea Life Aquarium and Whale Watching Cruise combo is available until October 31 and costs $99 per adult and $69 per child (four to 5 years). It includes morning entry into Sea Life Aquarium at Darling Harbour, a one-way rocket ferry from Darling Harbour to Circular Quay and a 1.30pm Captain Cook Cruises Whale Watching cruise departing from Wharf 6, Circular Quay. The combo offers savings of up to $40 per person. See captaincook.com.au or phone 9206 1111.
While it's a beautiful sunny day the water is choppy and some are feeling the effects quite dramatically, so take sea sickness pills before boarding if you are susceptible.