Portable charger — This compact unit is mightier than it looks: It’ll fully recharge your phone in an hour, so go ahead, livestream Childish Gambino for your Instagram followers. Kikkerland Pebble Power Bank, US$15
Water bottle — Collapse this bottle when it’s empty to save on space – even at its smallest, it holds 235 ml. Que Bottle (20 oz), US$25
Sunglasses — Not only do these fold up for easy storage in your bag, you’ll also channel Steve McQueen, who popularized this Persol style in The Thomas Crown Affair. Persol 714, $399
Earplugs — If you find yourself next to a ginormous speaker, pop in these earplugs, which come in a pack with three pairs and two cases. Matador Travel Earplugs Kit, US$10
Sunscreen — The stick format makes applying a breeze. Plus, this natural formula with jojoba, sunflower and vitamin E oils is reef–safe. Salt & Stone SPF 50 Sunscreen Stick, US$18
Hand sanitizer — No running water? No problem: This citrus–scented gel cleanses and leaves you with fresh, non–sticky hands. Aesop Resurrection Rinse–Free Hand Wash, $13
Fanny pack — Wear it around your waist or slung across your body – either way, this waterproof neoprene pouch holds everything you need for a day out. Dagne Dover Ace Neoprene Fanny Pack, US$85
Yes, you do need a fanny pack.