In Skull and Bones, the drawing on Old Treasure Maps will only show a facade of the island containing the treasure.
See also: All Old Treasure Map Locations | Skull and Bones Interactive Map
You will have to manually go to each outpost and use your Spyglass to bring up the outpost’s drawing, then compare that with the Old Treasure Map drawing. You’ll know if it’s the correct location if both hand drawn maps are identical to each other. However, if you’ve already visited all outposts, you can check that outpost’s drawing by just hovering over it on the map. This makes it much easier to find and match treasure maps to their locations.
Compare Map Drawing with Outpost’s Hand Drawn Image
