A sweep is either a contact sweep, a wire dragged through the water by one or two ships to cut the mooring wire of floating mines, or a distance sweep that mimics a ship to detonate the mines. The sweeps are dragged by minesweepers, either purpose-built military ships or converted trawlers.

Click a square, you get a number. That number is the number of how many mines are surrounding it. If you find the mine, you can open "unopened" squares around it, opening more areas. The numbers on the board represent how many bombs are adjacent to a square.