The former home of Sir George Grey, Mansion House sits in a historic reserve on Kawau Island, in the Hauraki Gulf, with gardens and an antique furnishings collection. The address is 5 Schoolhouse Bay Road. The website describes Grey's "gentlemen's estate", with the house, the gardens and easy walking tracks that take in Māori and colonial copper mining heritage. Walks include the remains of a coppermine engine house built in 1854, and lookouts above Ladies Bay and at the Coppermine.
Getting there is by water: water taxis and ferries run daily from Sandspit Wharf near Warkworth, and the trip from Westhaven Marina in Auckland takes about an hour. Boats can drop off and pick up only at the Mansion House historic jetty, and commercial boat operators need a permit to use it. Dogs are not allowed in the reserve, to protect kiwi and weka. The Mansion House Cafe is in the reserve and caters for weddings and other events, and the gardens are also a venue for them.