Refer the given story carefully and answer the question that follows:
King Metabo
King Metabo was a famous javelin thrower. One day he went out hunting with his daughter, Camille on his back. All of a sudden, the king was attacked by a band of enemies. He had to flee from them until he came to a fast flowing river, which he was unable to swim across because of his daughter on his back. It seemed as if he was lost until he thought of a way out. Tying his daughter to his javelin, he hurled it with all his strength to the other side of the river; then he dived in himself and swam across to where Camille was. His enemies were so amazed that they gave up the chase.
It was difficult for the king to swim across because____.