This activity is a good lesson in teaching map studies, and a good primer into the concept of longitude and latitude.
Take a local map, ie. from the internet. On this site, we have directions on the home page. You can print out the map, and make a grid on the map. You can set up the grid with A to E, and 1 to five across the top and side, and explain thoroughly how to identify the intersections between the two sets. Also, you can explain how to box out an area to determine the location of an area.
The object is to have the groups call out A1, E5, etc. And once you box in their home address, they call out battle ship. Then they can continue to play.
Variations, you can also call out bingo.
A more detailed Pacific ocean map can be printed, complete with battleships, destroyers, airplanes, and the printout can be use to as a grid using longitude and latitude lines. The lines can be called out with degrees longitude and degrees latitude, and when the intersections cross your hidden ship, you call out hit, or miss accordingly. When all five intersections of your battleship have been found, you call out you sunk my battle ship.