Marramarra National Park, Nature reserve in Hawkesbury region, northwestern Sydney, Australia.

Marramarra National Park is an 11,785-hectare protected area on the southwestern part of the Hornsby Plateau, a sandstone plateau cut by the Hawkesbury River, Berowra Creek, Marramarra Creek and Coba Creek. Mangroves line Marramarra Creek, while eucalypt forests and drier scrub cover the ridges.

Governor Arthur Phillip explored the Hawkesbury River here in 1789, and Gentlemans Halt, said to be his expedition's last camp, later became a small river settlement supplying the Hawkesbury and Macdonald colonies; it gained a provisional school in 1884. Remains of its road and wharf survive, as do old orchard traces at Marramarra Creek. The area was declared a national park on 28 December 1979.

The Darug people left rock engravings, cave art, grinding grooves, scarred trees and stone arrangements in the park. These traces of traditional life remain visible at several sites, showing how the land was used before European settlement.

You can reach the park by following Old Northern Road from Wisemans Ferry or by taking Galston Road through Galston Gorge when arriving from Hornsby. Different entry points offer varying access to trails and water activities, so plan your route depending on what you want to explore.

Gentlemans Halt, on the Hawkesbury River, was the last camp of Governor Arthur Phillip's second expedition up the river in 1789. A small settlement later grew there to supply the colonies on the Hawkesbury and Macdonald rivers, and gained a provisional school in 1884. Only remnants of its road and landing place survive.