Everybody seems to have forgotten the expedition that I organized in the mid 1980's. We had a government permit and a well equipped group. We spent three weeks exploring the island and discovered a rock map that led us to what I feel was the cave in which the treasure of Lima was hidden in 1820. We were the 378 th expedition and the only one to put the clues together leading us to the map and cave, far away from the normal search areas. I published a small book with many photographs, maps, clues and much more information. There was a government agent with us the entire time. Months after our expedition, the Costa Rican government requested members of our group to return to Cocos and assist them in a search for several lost tourist on the Island, because we had more experience than the half dozen solders stationed there had.
Most people restrict their time on the island to the coastal area due to the extremely difficult terrain, not us, we went deep into the interior, even seeing a WWII bomber that was wrecked on one of the mountain tops.
Good Luck on your attempts.
Richard Byrd Ray