Secluded like a storybook forest, this 100-acre state park offers camping, cabins and various gentle trails. Set amid native trees at 2000ft, it's a quiet spot with few visitors, maybe too deserted for solo travelers. But it's fantastically lush and a great place for group or family camping. For a sightseeing stop, take the easy 0.75-mile Nature Trail, which passes through old ohia forest, where some trees measure over 3ft in diameter. The path can be overgrown so watch for the established trail.
The park comprises two overall trail systems (see the large map near the cabins). The Nature Trail starts where the road by the cabins ends. Skip the Dryland Forest Trail, which only goes 100yd, and the Arboretum Trail, which is so overgrown that you might get lost. A small Polynesian garden contains a dozen of the original 25 canoe plants, introduced to Hawaii by the original Polynesian voyagers for food, medicine and clothing.
The second, more-interesting trail system leads into the adjoining forest reserve with old-growth forest and tremendous tree ferns. It starts along Robusta Lane, on the left between the caretaker's house and the campground, and goes about 600yd to the edge of Kalopa Gulch, through a thick eucalyptus forest. The trail continues along the gulch rim for another mile, while several side trails branch off and loop back into the recreation area via the Perimeter Trail. Signage is confusing so you should sketch the map near the cabins for reference along the way. You can go over 4 miles on these scenic but spottily maintained trails.
For camping (per night residents/nonresidents $12/18), you must reserve a permit in advance. Group cabins (per night residents/nonresidents $60/80) sleep up to eight people and include bunk beds, plus shared restrooms, hot showers and kitchen.
To get to the park, turn mauka off the Hawaiʻi Belt Rd near mile marker 42, at Kalopa Dr. Follow park signs for 3 miles.