Freshwater Beach is one of the best Snorkeling spots in Sydney. The very beginning of Queenscliff Bay on the left side of the beach when facing the ocean is protected by a reef. A huge diversity of fish and saltwater invertebrates inhabit these rocks and it is common to find schools of Yellowfin Breams and Stripeys. This Beach is not as well protected as Clovelly or Shelly Beach and it is thus not the best place to learn snorkeling. But it also means that the water is very clear and only getting cloudy near the beach.
Compilation of videos taken with a GoPro Hero 4 Black Edition while snorkeling in Freshwater Beach/Queensclif Bay:
Freshwater Beach is very close to Manly but it is not as famous. There are less people swimming and snorkling which is very enjoyable. I haven't tried to snorkel on the right side of the beach yet but the rocks on the left side when facing the ocean are suitable for swimming.
Freshwater Beach is one of the northern beaches, very close to Manly. Parking is usually not very difficult if you don't mind walking a few minutes with your flippers and goggles in your hands.