This walk can really only be attempted 2 hours each side of low tide. Park at either Fishermans Cove or Tindalls Bay and the walk 2km each way or arrange a car at each end to make it a one way walk.
Once you get to Coal Mine Bay find the trail which follows the fenceline up to the point. There is no need to cross any fences or access private property. The cache is a hidden few metres off the path. It is close to the edge of a very steep drop but there is no need to go past/below the large pohutakawa tree.
Enjoy the view from up here and then maybe celebrate with a swim after you get back to the beach.