This is important as it allows limited intelligence of other friendly ships as well as enemy ships. Shore installations can also be defined and edited. A terrain editor allows the coastline, hills and submarine contours to b entered. If this is done the game runs slower, but can allow for running aground. There is quite a lot of work in setting up a game, but it gives a good result.
Limited intelligence is given of all other ships which can be seen.
Visibility rules may leave a player unaware of other vessels. Order can be given for boat actions - each boat lowered being assigned to a group of boats which can be given a single order. There is an option to allow two computers to be linked in a master-slave configuration to allow simultaneous input. I have never used this option. Once the orders are entered movement is calculated.