Minecraft wiki entry for Explorer_Map, associated text: There are three types of explorer maps: woodland, ocean, and buried treasure. The maps differ from a normal map, in that it shows the area's land-water outline, as well as an orange striated (striped) texture for areas below sea level, and the blank map texture for land above sea level. The maps show a section of land that contains a woodland mansion, monument or buried treasure respectively. This may not be the nearest such structure to the player. The structures are displayed as a small icon. If the player icon is smaller than it would be on a normal map, that means the player is a great distance away. When the player is less than 1027 blocks away from the map border, the icon returns to the proper size. When the player reaches the map's area of land (512×512), the map fills in like a normal map.