South Mona Vale Headland (officially Robert Dunn Reserve) is a fully fenced, cliff-top off-leash park perched above Mona Vale Beach on Narrabeen Park Parade. It is one of the Northern Beaches' most beloved 24/7 off-leash spaces—dogs can run free all day, every day, with no time restrictions, no trial rules, and no Ranger-enforced windows. The large grassy plateau is sheltered from the worst of the nor-easter while still delivering sweeping panoramic views across Mona Vale Beach, Bungan Head, and the Tasman Sea.

Officially managed by Northern Beaches Council, the reserve is fenced along the entire eastern cliff edge except for a wide concrete stairway that descends directly onto the sand at the southern end of Mona Vale Beach. This stairway is the official access between the headland and the beach below, meaning the two locations are contiguous but functionally separate—you can start your visit on the headland grass, then walk your dog down the stairs for a quick paddle in the shallows before heading back up (leash rules apply separately for each side of the stairs, as the beach operates on a timed trial while the headland is always free).

The social atmosphere is friendly and low-pressure, with most local owners staying for 45–60 minutes while their dogs tire themselves out chasing balls, greeting other dogs, or just doing zoomies across the grass. The shared asphalt pathway along Narrabeen Park Parade is also popular with joggers and prams, so Council signage asks owners to be mindful of pedestrians crossing through the reserve. For a full half-day outings, you can pair this stop with a northward coastal walk towards Newport Headlands, a coffee at one of Mona Vale's village cafes (many with outdoor seating), or a timed visit to the adjacent South Mona Vale Beach off-leash trial during its approved morning and evening windows.