"We have three Marine Sanctuaries and a Marine National Park in Port Phillip Bay and each, in its own way, is unique."

Peter Johnstone, Marine Ranger, Parks Victoria

At the entrance to 1950 square kilometre Port Phillip Bay there are pockets of very deep water ranging to 90 metres. The turbulence of incoming and outgoing tides support some interesting sea creatures such as Bi-valve Shellfish, and marine plants such as five metre long kelps.

Near the entrance of the bay are a bunch of small sandy islands that are possibly Victoria's biggest pelican breeding site. Nearby there is a deep hole that is an underwater geological mystery and is richly encrusted with sea sponges, around which reef fish and SCUBA divers swim.

At the top of the bay, near Melbourne, the waters are much shallower – two to three metres in places. But the rock platforms that are exposed at low tide are just as fascinating to rock-ramblers who can hop across the rock shelves and peer into the shallow waters.

Even in the shallows, the sea-grass meadows are vital habitat for fish, colourful sponges and extraordinary creatures such as the Nudibranch, the small orange and blue spotted sea slug.

The “no take” Marine National Park and Marine Sanctuaries were declared in 2002, in a far-sighted move to protect significant areas representative of the strange and engaging marine ecology of the bay. Parks Victoria Marine Ranger, Peter Johnstone says, "Port Phillip Bay represents a marine bio-region that is technically defined as an embayment bio-region, and it has certain characteristics that are found nowhere else."

The areas selected for protection all have distinct attributes and all were undeveloped in terms of piers or jetties. "The Marine Park and sanctuary system means we're able to protect them so that they will still be the same in 50 to 100 years time," says Peter.

Of the four protected marine areas, the 3580 hectare Port Phillip Heads Marine National Park is by far the biggest and it incorporates six different areas.

Swan Bay, a shallow waterway is of international significance and has, says Peter, "mudflats, sea grass meadows that are hundreds of hectares in extent, and that serve as nurseries for 44 fish species including whiting, flatheads and snapper." Swan Bay also supports large populations of sea-going and wading birds.

Nearby Point Lonsdale has a large, flat sandstone rock platform "that drops away underwater very quickly to 30-40 metres. It is a place of classic, picture book rockpools. Because the tidal currents and rich nutrients make it so dynamic, it is popular with divers because it has many different fish and spectacular sponges."

Like all the Marine Park venues in the bay, the wonders of the deep and shallow water are included on the itineraries of sailing and motor-boat tours, or are accessed by self-propelled craft such as sea kayaks or with adventure tour operators who take divers out to the sites. Dolphin, seal and birdwatching tours are also popular with park visitors.

Point Nepean, on the opposite, eastern point of the Bay, has, says Peter, similar characteristics to Point Lonsdale and a similar view of the three kilometre wide bay entrance, “The Rip.” Nepean Bay has fish nurseries, while the ocean side has extensive limestone rock platforms that drop into deep water. Former Prime Minister Harold Holt was last seen on one of these platforms in 1967.

Pope's Eye, a rocky island built in the 1880s, was intended as a fortress but it was never completed. "It has been a marine sanctuary since the mid-1970s," Peter says. “Many sea birds, including gannets now call it home.”

The Portsea Hole is a geological depression that drops to 30 metres depth and is home to very different marine plants and reef fish. It is a wonderful area for experienced divers to explore.

The sandbanks that form Mud Island are quite fantastic for their pelican and Fairy Tern rookeries. "I've seen 400 pelicans there," Peter says. It also has sea-grasses and seaweeds and a large enclosed wetland inside the sandbanks.

At the head of the Bay, are three different sanctuaries: The 115 hectare Ricketts Point Marine Sanctuary , off suburban Beaumaris, has a combination of sandstone rock shelves, sandy beaches and a series of offshore reefs "on which you can sometimes see 100 sea birds roosting."

Rickett's Point, according to Peter, "is a great place for snorkelling, rockpooling and for seeing not only the birds, but a different assortment of colorful seaweeds. There are also lots of shellfish and sea snails. Protected school fish, such as whiting and garfish, come right into the shallows."

In an area near Williamstown, one of Melbourne's first village settlements, a rifle range protected an area of coast for 100 years or more. The 30 hectare Jawbone Marine Sanctuary has mangrove stands on basalt rock platforms. Behind it is a salt marsh teeming with juvenile fish and small invertebrates. The sanctuary attracts birds including cormorants, pelican and White-faced Herons.

Point Cooke Marine Sanctuary abuts former farmland which protected it while many neighbouring areas were developed. Peter says its basalt rock platform, sandy beach environment and shallow water makes it a very popular venue for snorkelling. "It has a lot of orange and red sea sponges, a good variety of small fish and sea-weeds."

While these sanctuaries are only remnants of the greater marine ecology of Port Phillip Bay…each in its own way is a place of great ecological significance. Peter believes we are lucky to be able to explore them while at the same time respecting their protection.

For further information on the Port Phillip Bay Marine National Park and Marine Sanctuaries please contact Parks Victoria info@parks.vic.gov.au or visit our website: www.parkweb.vic.gov.au.