Count of Monte cristo how did Dantès escape prison

When abbe Faria died, the sack in which he was put in gave Dantes an idea. He took abbe Faria out of the sack and placed him behind the fireplace in his cell. Dantes put himself in the sack and was taken by the guards for the burial. After they threw the sack in the ocean Dantes cut the sack open took a deep breath and jumped in the ice cold sea then he was taken by a ship and he escaped.