army training area...... but its not gaurded. i used to ride it all the time when i lived in hawaii. its got some long and climbs and downhill. its not too technical allthough im sure you could find some if you looked. you can change you routes, the longest combo i did was 30 miles so its up to you...
get of the h2 at schofield barracks and head south on kamehameha, take a left on higgons road. then you will see a fenced in complex with large tents. the entrance to the system is behind the tents. there is a golf course across from it
http://www.singletracks.com/item.php?c=1&i=4479