The green lines indicate the various routes mentioned in the latest log entry. This chart is on a scale that doesn't show all the shoals and rocks and reefs, so I know it looks as though we can just drive anywhere we like, but that light-blue area is the Great Bahama Bank, and between us and just about anywhere lie coral heads and sandbanks too shallow for us to go over. If you want to locate this region on your own atlas, the yellow bit in the upper left is the edge of Andros Island, which is big enough to make it onto most regional maps.