Three o'clock
All around them tossed and streamed and writhed long , black aprons of kelp . They were passing over a sunken ledge . Soon it lay behind them ; the kelp vanished and the waves grew lower . Three o'clock went by ; then four . The afternoon was waning . The thick , woolly gray that surrounded them assumed a more somber shade . Night was coming , pitchy and starless , doubly so for the two lost boys , adrift on the open ocean .