Sentence:  Mark 's thoughts must have been keeping silent pace beside his own , climbing the same crags in dirty <WSD>white</WSD> sneakers , clambering out on top of the headland and coming upon the sudden glinting water at the same instant . 
Meaning of the word marked with <WSD> tags:  the quality or state of the achromatic color of greatest lightness (bearing the least resemblance to black)