Don't Rock the Boat

The boat rocked back and forth, on and on, side to side, like some old lady's rocking chair or the pendulum of a grandfather clock.
       At least the humming had finally died down.
       "Think it's safe?" he dared to whisper.
        Not two seconds after the words left his mouth when pale, white arms shot out of the water, wrapped around his body, and dragged him back under the waves.
        Blood rose to the inky surface.