I don't know what is there not to get. Why people are so confused about this film. It's very simple.
It's said right in the beginning "Remember the story I used to tell you when you were a boy? About a young prince, a knight, sent by his father, the King of the East, west into Egypt, to find a pearl. A pearl from the depths of the sea. But when the prince arrived, the people poured him a cup that took away his memory. He forgot that he was the son of the king. Forgot about the pearl. And fell into a deep sleep.The king didn't forget his son. He continued to send word, messengers, guides. But the prince slept on."
And this is basically what this film is about. Trying to wake up, trying to find yourself. Seeing your lived life flashing by before drowning, and feeling the loss and regret of wasted life and opportunity. Now seeing the messages and messengers that were sent to you, but you were blind. You were asleep and refused to wake up. You wanted to dream. You could have been anything, but you didn't choose anything. You were lost and you didn't even know you were lost.
In the very end he chooses. He chooses to try again. And pushes himself to the surface of the water.
In the very end he chooses. He chooses to try again. And pushes himself to the surface of the water.