Old Man and the Sea: A little over halfway

As you may have guessed from my blog title, I am a little over halfway done with Old Man and the Sea and have decided to post my thoughts on it.

First: Hemingway's writing style.  In my pre-reading, I learned Hemingway was known for a very simple writing style.  I wasn't expecting a lot of descriptions in this book, but the way he describes the old man on pages 9-10 was very detailed and helped me picture him perfectly.  The conversations between him and the boy were written very simply, with nearly no interruptions between the dialogue.  It was different than what I'm used to, but I liked it.  One thing I found interesting was although the reader learns the names of both characters, they are only referred to as the old man and the boy.  Otherwise, I actually don't find the book too simple.  He actually spends quite a bit of time elaborating on a plot that is rather simple.
Second: the plot.  Like I said, it is very simple.  An old man goes fishing and... yeah, he goes fishing.  He's had an "unlucky" streak when he couldn't get any fish, so when he finally does get a fish, he hangs on to it for dear life, actually spending days on end not letting it go.  And well, not much else has happened.  He talks some to himself (and a little to the fish, but I don't really blame him because I would be going insane if I was on that boat), remembers the good old days in Africa, and occasionally expresses loneliness.  It seems to me Hemingway is making a point about perseverance, but I don't think I'm far enough in the book to pinpoint everything he is trying to say.
Lastly: predictions.  I have a feeling the old man is going to loose his fish one way or another but still be okay with it.  I think I've heard this book is a tragedy but I don't really see how it could be that sad...  Anyway, I'm interested to see how/ if Hemingway deepens the story, how it ends, and finding his purpose for writing it.