Mine Sweepers.

In Defence of the Seas.

We tend to forget this form of warfare still exists? 
Former British Princess Diana fought very well to try to ride the world of land mines and other similar weapons, with some success. But the Seas are another area, where it would seem unlikely for the innocents to be effected?

A boat was developed prior to World War-I (1914-18) in which to both track enemy mines and also to lay their own. Thousands of such vessels have been built since World War-II(1939-45) to do the same. 

It was the development of radar and its sea equivalent Sonar that has pushed new design. Nearly every navy in the world employ minesweepers, either in that primary role or joint such as patrol.

Today the occasional World War-I mine does surface in the English Channel and the North sea. Fishing trawlers have the unfortunate task of drawing them up from the sea bed in their nets.