You whip your tail around and start pushing around the chest until the Water Elemental wakes up. "HEY! WHAT THE HELL ARE YOU-" It then realizes that the chest is open. "I... I'm free... Did you open the chest?" You nod your head. "Oh thank you! I've been trapped in there for centuries! If there is any way I can thank you, let me know!" You have many questions, and if this elemental is as old as it says it is, perhaps you could get some answers.