There's some nice roads up that way. The only problem with the gorge you're talking about, is that it melts during the summer! 
Next time, take the turn off south of the gorge & catch the ferry across the harbour to head down the coast through the Kauri forests & Dargaville. Good stuff.
"Women & cats will do as they please, and men and dogs should relax and get used to the idea." Robert A. Heinlein
"Do not meddle in the affairs of cats, for they are subtle and will piss on your computer." Bruce Graham
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