All sides would engage in vigorous mining and counter-mining duels. The dry chalk of the Somme was especially suited to mining but with the aid of pumps it was also possible to mine in the sodden clay of Flanders. Specialist tunnelling companies, usually made up of men who had been coal miners in civilian life, would dig tunnels under no man's land and beneath the enemy's trenches. These mines would then be packed with explosives and detonated, producing a large crater. The crater served two purposes; it could destroy or breach the enemy's trench and, by virtue of the raised lip that they produced, could provide a ready-made "trench" closer to the enemy's line. When a mine was detonated, both sides would race to occupy and fortify the crater.

If the miners detected an enemy tunnel in progress, they would often drive a counter-tunnel, called a camouflet, which would be detonated in an attempt to destroy the other tunnel prematurely. Night raids were also conducted with the sole purpose of destroying the enemy's mine workings.

The British detonated a number of mines on July 1, 1916, the first day of the Battle of the Somme. The largest mines—the Y Sap Mine and the Lochnager Mine—each containing 24 tons of explosives, were blown near La Boiselle, throwing earth 4,000 feet into the air.

At 5.10 am on June 7, 1917, 19 mines were detonated by the British to launch the Battle of Messines. The average mine contained 21 tons of explosive and the largest, 125 feet beneath St. Eloi, was twice the average at 42 tons. The combined force of the explosions was supposedly felt in England. As the Chief of Staff of the British Second Army, General Sir Charles Harrington, commented on the eve of the battle:

The craters from these and many other mines on the Western Front are still visible today. Three further mines were laid for Messines but were not detonated as the tactical situation had since changed. One blew during a thunderstorm in 1955, the other two remain to this day.