How does Rainsford navigate his way while swimming in the dark?

The current makes it impossible for Rainsford to swim back to the yacht. As salt water entered Rainsford's mouth, he begins to panic. He watches helplessly as the yacht sails away, leaving him alone in the dark water. Remembering the sound of the shots, he begins swimming in the direction of their origin. While trying to swim in that direction, he hears an animal cry out in anguish. Rainsford can’t identify the animal that made the sound.

As he continues to swim toward the sound, more gunfire fills the air. After ten minutes of struggling through the water, Rainsford eventually reaches the shore. He painfully drags himself out of the water with the little energy he has left.