Sentence:  The deck below me was littered with chests, sea boots, and odds and ends of clothing, while farther aft considerable water had found entrance through the scuttle hole, and was <WSD>slushing</WSD> back and forth as the bark rolled. 
Meaning of the word marked with <WSD> tags:  To slosh or splash; to move as, or through, a slushy or liquid substance.