Sentence:  But as the boat stuck in the bottom and refused to stir, he suddenly dropped his hold, and with an "Avance done!" gallantly <WSD>slushed</WSD> his way into the water alongside, in his Sunday trousers, lifted the gunwale and started her afloat, amidst a shower of final "Au revoirs," and the rose "chaloupe" moved with noiseless smoothness down the current. 
Meaning of the word marked with <WSD> tags:  To slosh or splash; to move as, or through, a slushy or liquid substance.