"I was in time to catch an evanescent glimpse of my white hat left behind to mark the spot where the secret sharer of my cabin and my of thoughts, as though he were my second self, had lowered himself into the water to take his punishment; a free man, a proud swimmer striking out for a new destiny" (2.205).
At the end of "The Secret Sharer," Leggatt jumps into the ocean and swims for the nearby island of Koh-ring. But all the captain can see when he looks into the dark water is his own white hat, which he lent to Leggatt. The fact that he never sees Leggatt again adds to the idea that Leggatt was only ever a figment of his imagination. But if this is the case, then this scene also shows that the captain has gotten to a mental place where he doesn't need Leggatt anymore. He no longer doubts himself or feels lonely, but instead commands his ship with confidence. He talks about Leggatt as though he's a free man starting a new life, but the truth is that the captain could just as easily be talking about himself. Man, maybe we should all find an imaginary friend to help us with get over our insecurities…Conrad certainly makes a good case for that in this story.