Depends on the map and the purpose. Lat and Long is the same no matter how you look at it. The plotting of the map is what ever the intent was. The ocean surface is well, water. Water is water. IF you are talking position of an island, then that is a land mass like any continent and the accuracy is what the intent was. Now finding an island on the water, the position of the island as a locator, that is a different issue. Reefs and such, some are quite accurate once you reach the reef, but finding the reef is another issue. Reefs should be close since if you happen to navigate into coral, then you may loose your ship. But as Tayopa said, finding an island in the open ocean, well .25 - .50 mile resolution is good enough and I would be surprised if it was that close in WW2.
Land Ahoy ! !
Z
