Hole is an Adventure Map feature that can be located on any land tile - that is: not water. They can either be placed on the map by the map-maker, or they appear after a hero has dug the ground. Digging and holes have two purposes. Firstly, digging is typically the only way to find the grail artifact (another possibility is to find a hero with the grail artifact). Secondly, tiles with holes in them cannot be disembarked with a boat. This makes digging holes on the shoreline in order to prevent enemy heroes' invasions a strategic feature.