Big Drop Off, just what the name implies is really big. About 30 feet (10 meters) from the mooring buoy to the east at 35 feet (12 meters) a large chain connected to a 6 foot (2 meter) steel sphere can be seen. This chain and ball was used during WWII to prevent the Japanese from entering the waterway leading to German Channel. Lieutenant Barnum from the US Navy conducted the Operation. The chain and ball on Big Drop Off was a mystery for 40 years until newly appointed Admiral Barnum returned to Palau in 1986 and told his story.