Luggage and bags:
Backpacks are probably best.
Clothing/Shoes/Weather Gear: Swimsuits, walking shoes.. the usual stuff!
Toiletries and Medical Supplies: Stores on the island but probably best to bring your own as prices might be higher
Photo Equipment: As above
Camping/Beach/Outdoor Gear: Camping is available on the island so bring your equipment if you wish to do this.
Good walking shoes. And a coat for possible and fast weather changes.
Photo Equipment: Plenty of spare film, although you can buy on the island.
Miscellaneous: Lip cream and sun protection.
Insect repellent, as in summer the mudflats have lots of insects.