This is hands down the best day hike in Auckland!
Be prepared for lots of stairs but absolutely stunning coastal views.
You can start the Omanawanui track from the beach entrance for Signal House track at the very end of Whatipū road, or you start at the smaller carpark along Whatipū road (this has space for about 4 cars). The gravel road to get out here can be quite narrow and windy so be prepared to take it slow.
Extra details:
Distance: 3km one way
Elevation: approx 350m elevation gain
Walk time: approx 2-2.5hrs one way