O'ahu has a varied, extensive, and distinctive network of mountain hiking trails. Stuart M. Ball, Jr., author of The Hikers Guide to O'ahu, explores the history behind many of the island's trails, beginning with early Hawaiians who blazed routes for traveling, plant and wood gathering, and bird catching. Sugar plantations constructed paths to access ditches that tapped stream water for thirsty cane. The U.S. Army built trails for training and island...