The new sea-warfare has developed a scheme of offence that renders our inshore waters peculiarly fraught with peril to navigators. The coast-line is no longer a defence and protection; rather, by limiting sea-room in manoeuvre, the shoals and rock-bound beach have turned ally to the enemy. Sea-mark and headland provide a guide in estimating the run of a torpedo; note of a point definite, on which sea-routes converge, is of value to a submarine commander. Even in the shallower waters--depths in which a torpedo attack would be difficult--an equally deadly offence may be maintained. The run of the sea-bottom in the channels offering a good hold to slipped mine-moorings, it was not long before the enemy had adapted submarines to continue the minelaying that our command of the surface had stopped. While new and larger U-boats are sent abroad on the trade routes, special submarines, less encumbered by the stores and equipment that longer passages would demand, make frequent visits to the fairways to sow a freight of mines. No section of the channels holds sanctuary for the coaster. Close inshore, as in the offing, is all a danger area, open to the stealthy visits of the submarine minelayers. Right on the Mersey Bar, the Liverpool pilot steamer went up with a loss of forty lives; remote West Highland bays have echoed to the crash of mines exploded; seaward of the Irish banks, the deeps are alike dangerous. Counter-measures there are (services as efficient and resourceful in life-saving as those of the enemy are cunning and viciously ingenious in murder), but even the gallantry and skill and untiring efforts of our minesweepers cannot wholly clear the immense water-spaces. Mechanical contrivances--the Otters--are valuable, and aid in fending the mines, but (the sea-bottom being foul with wreckage) they are often a danger to their carriers. There is ever the harassing uncertainty which no vigilance may allay. The sheer relief of passing over the hundred-fathom line to the comparative safety of the deeps of ocean is never experienced by the cross-channel captain.