land of plenty

"We haven't one chance for life in a hundred thousand if we don't find food and water upon Caprona. This water coming out of the cliff is not salt; but neither is it fit to drink, though each of us has drunk. It is fair to assume that inland the river is fed by pure streams, that there are fruits and herbs and game. Shall we lie out here and die of thirst and starvation with a land of plenty possibly only a few hundred yards away? We have the means for navigating a subterranean river. Are we too cowardly to utilize this means?"