If you happen to be taking a drive through Maroubra, why not keep going up Anzac Parade, past Long Bay Gaol, past the Little Bay Golf Course, until you get to the end, where you will hit the gorgeous La Perouse. Although there are a few beaches in this area to check out, there is also the foot bridge (which goes out to Bare Island, which is only open on certain days for tourists as a paid tour). Walking across the bridge is a wonderful experience, with the structure deeply enriched in Australian History.
Now, under the bridge is where you will find an excellent area to go snorkeling, diving, or oyster collecting! It is very common to see groups of people exploring in the water under the bridge on any given day. On the other side of the bridge you can continue to walk around the cliff face of the island, which provides a stunning scenic experience. This area is amazing for fishing, picnics and just relaxing.
So do yourself a favour, keep driving up Anzac Parade and don't stop until you hit this golden piece of land.