Solitary Islands Marine Park is a marine park in New South Wales State waters, Australia. It adjoins the Solitary Islands Marine Reserve (Commonwealth Waters) and was declared under the Marine Parks Act 1997 (NSW) in January 1998. Prior to this it was declared a marine reserve in 1991. The Park was one of the first declared in NSW and stretches along the northern NSW coast, from Muttonbird Island, Coffs Harbour, to Plover Island near Sandon River, 75 kilometres to the north. It includes coastal estuaries and lakes and extends from the mean high water mark, to three nautical miles out to sea, covering an area of around 72 000 hectares. There are five main islands in the Park, North Solitary Island, North West Solitary Island, South West Solitary Island (Groper Island), South Solitary Island and Split Solitary Island, as well as other significant outcrops such as Muttonbird Island and submerged reefs.
On 15 May 1770, Lieut. James Cook sailed past the Solitary Islands and noted their position in his journal, “Between 2 and 4 we had some small rocky Islands between us and the land the southernmost lies in the Latitude of 30°10' and the northernmost in 29°58' and about 2 Leagues or more from the land.” He named them the "Solitary Isles" on his chart.
The Solitary Island Marine Park contains a diverse range of habitats including intertidal and subtidal reefs, soft sediments, beaches, seagrass beds, mangroves, saltmarsh and open waters, which support a large variety of fauna and flora. The northern section of the marine park borders the Yuragir National Park, between Sandon River and Red Rock, which contains several open and closed lakes and lagoons. As well as bordering Moonee Beach Nature Reserve, Garby Nature Reserve at Arrawarra, and Coffs Coast Regional Park, it also incorporates Muttonbird Island Nature Reserve, Split Solitary Island Nature Reserve, South West Solitary Island Nature Reserve, North West Solitary Island Nature Reserve, North Rock Nature Reserve, North Solitary Island Nature Reserve and the South Solitary Island Historic Site which covers 11 hectares and incorporates the lighthouse and keepers cottages built in 1879. Prior to European settlement, none of these islands had been inhabited, burned or subject to grazing animals. A fragile balanced ecology had built up over centuries.