Maj. Doug Strahan, an operations planner with G-3, U.S. Marine Corps Forces, Pacific, and his son open one of the oldest geocaches hidden on Oahu, Oct. 12, 2013. Strahan said ammunition cans are good containers for geocaches. (U.S. Marine Corps photo by Kristen Wong) - Maj. Doug Strahan, an operations planner with G-3, U.S. Marine Corps Forces, Pacific, and his son open one of the oldest geocaches hidden on Oahu, Oct. 12, 2013. Strahan said ammunition cans are good containers for geocaches. (U.S. Marine Corps photo by Kristen Wong)