Get a soft cooler with a dry pocket.

Yes, you want a soft-sided cooler with a separate dry compartment for electronics and sunscreen. Hard coolers are heavy, hard to carry in sand, and everything ends up wet from melted ice. A soft cooler with a dedicated dry zone keeps your phone dry and your sunscreen from floating around in ice water. Something like the Yeti Hopper or the Pelican Elite soft cooler works well. Don’t cheap out too much—a leaky cooler defeats the purpose. Your phone will thank you.