Here is a goal: How can I make ice last longer in an ice chest?

How would you accomplish this goal?

Possible answers:
1). When you go to the beach and take your cooler with you, sprinkle salt on the ice, and keep the lid shut so that it stays frozen for much longer.;
2). When you go to the beach and take your cooler with you, sprinkle salt on top of the outside of the cooler, and keep the lid shut so that it stays frozen for much longer.;
1).