Sentence:  Mark 's thoughts must have been keeping silent pace beside his own , climbing the same crags in dirty white sneakers , clambering out on top of the headland and coming upon the sudden glinting <WSD>water</WSD> at the same instant . 
Meaning of the word marked with <WSD> tags:  binary compound that occurs at room temperature as a clear colorless odorless tasteless liquid; freezes into ice below 0 degrees centigrade and boils above 100 degrees centigrade; widely used as a solvent