They thought of it; and the thought filled them with apprehension. From the observations they had made before sunset, they knew that the shore could not be near--not nearer than three miles--perhaps four. Even with free footing, the true direction, and a clear view of the path, it might have been a question about time. They all knew enough of the sea to be aware how rapidly the tide sets in--especially on some foreign shores--and there was nothing to assure them that the seaboard of the Saaera was not beset by the most treacherous of tides. On the contrary, it was just this--a tidal current--that had forced their vessel among the breakers, causing them to become what they now were,--castaways! They had reason to dread the tides of the Saaera's shore; and dread them they did,--their fears at each moment becoming stronger as they felt the dark waters rising higher and higher around them. CHAPTER VI. WADE OR SWIM? For a time they floundered on,--the old sailor in the lead, the three boys strung out in a line after him. Sometimes they departed from this formation,--one or another trying towards the flank for shallower water. Already it clasped them by the thighs; and just in proportion as it rose upon their bodies, did their spirits become depressed. They knew that they were following the crest of the sand-spit. They knew it by the deepening of the sea on each side of them; but they had by this time discovered another index to their direction. Old Bill had kept his "weather-eye" upon the waves; until he had discovered the angle at which they broke over the "bar," and could follow the "combing" of the spit, as he called it, without much danger of departure from the true path. It was not the _direction_ that troubled their thoughts any longer; but the _time_ and the _tide_. Up to their waists in water, their progress could not be otherwise than slow. The time would not have signified could they have been sure of the tide,--that is, sure of its not rising higher. Alas! they could not be in doubt about this. On the contrary, they were too well assured that it _was_ rising higher; and with a rapidity that threatened soon to submerge them under its merciless swells. These came slowly sweeping along, in the diagonal direction,--one succeeding the other, and each new one striking higher up upon the bodies of the now exhausted waders. On they floundered despite their exhaustion; on along the subaqueous ridge, which at every step appeared to sink deeper into the water,--as if the nearer to the land the peninsula became all the more depressed. This, however, was but a fancy. They had already passed the neck of the sand-spit where it was lowest. It was not that, but the fast flowing tide that was deepening the water around them. Deeper and deeper,--deeper and deeper, till the salt sea clasped them around the armpits, and the tidal waves began to break over their heads!