Only 45 minutes north of Wellington, this park covers 2860 hectares. It features steep, bush-clad hills, the Hut River Gorge and centuries-old rata, rimū and beech (New Zealand native plants). I recommend walking the Loop Walk, a 15min return easy walk over the swing bridge and through the rainforest, after visiting Rivendell, which is a Lord of the Rings movie location nearby.
The Kaitoke campground is also a great place to stay if you want to spend more time in the region, to swim in the river or go rafting.