Sentence:  Carried somehow, somewhither, for some reason, on these surging <WSD>floods</WSD>, were these travelers, of errand not wholly obvious to their fellows, yet of such sort as to call into query alike the nature of their errand and their own relations. 
Meaning of the word marked with <WSD> tags:  A (usually disastrous) overflow of water from a lake or other body of water due to excessive rainfall or other input of water.