The water rippled and tore, and pulled all ways at once; and the fragile shell, unable to go all ways at once, shook and quivered with the shock of resistance.
It veered nervously to the right and left, but Frona held it with a hand of steel.

A yard away a fissure in the rock grinned at them.

La Bijou leaped and shot ahead, and the water, slipping away underneath, kept her always in one place.

Now they surged out from the fissure, now in; ahead for half a yard, then back again; and the fissure mocked their toil.
Five minutes, each of which sounded a separate eternity, and the fissure was past.

Ten minutes, and it was a hundred feet astern.