I am pretty keen on water, a lot of which probably comes from having grown up
in Manly which sits with a harbour on one side and ocean on the other.
For years I've loved snorkelling and swimming around Manly Cove (like at Delwood Beach shown in the picture) and the Northern Beaches of Sydney. The variety of marine life around Manly Cove now is pretty amazing since they sent the ocean outfall a couple of hundred kilometeres further out to see a few years back..
In the warmer months (roughly Setpember to April), I enjoy body surfing at Freshwater, Narrabeen, North Curl Curl and other places along the east coast of Oz. There's pictures of some of these places in my Sydney Coast tour.
Hiring a canoe or rowboat is also great fun (e.g. at Narabeen Lakes).
Another bit of water fun, particularly if you can find it on a not-so-crowded
day, is the International Aquatic Centre. This has been built at Homebush for
the Sydney 2000 Olympic Games (hey, only a thousand or so days to go now!).
As well as two great olympic-style pools, they have rapids, fountains in
the middle of pools, waterslides and spas. Good fun all year round.