The skavid map is required to successfully navigate the Skavid caves around Gu'Tanoth. Without possession of this map, players entering into one of the Skavid caves will immediately exit the next cave entrance in a clockwise direction, the last one being next to Toban's island, before starting at the north-west cave again. Players do not need to read the map to enter the Skavid caves, only have it in their inventory.
During the Watchtower quest, you obtain the map by visiting the ogre city guards all the way at the end of the path leading into Gu'Tanoth. You will need a rock cake to bribe an ogre guard, 20 coins to pay a guard to let you jump over a broken bridge, and a death rune to give to a city guard in exchange for the map.
After the quest, if you lose the map you can get another one from a city guard for free. A rock cake and 20 coins WILL NOT be required to reach the city guard who will give you another. The same guard who gave you the riddle mentioned above. No other guards replace the map.
Reading the map
If you choose to read the map, you see a highly stylised map that approximately shows the entrances to the caves.