Waterproof shoes such as rubber flip-flops, crocs or other sandals are excellent for Stone Town because if it rains your feet will get drenched no matter what you're wearing. They are also easy to remove and some restaurants are Arab-style and require shoes to be removed at the door.
Rainy season in October - January so a poncho or umbrella is handy at this time of year.
Toiletries and Medical Supplies: Tampons are hard to find so ladies make sure you have your supply if needed.
Camping/Beach/Outdoor Gear: When in town shoulders and knees should be covered by both women and men . Long shorts and T shirts are fine but halter-tops and miniskirts are insulting to the local population and will land you unwanted stares and comments.
Once on the beach it is fine to wear your normal beach gear - but cover up if you go to a village or shop.
Miscellaneous: The local electricity is the same as England at 220/230 but it is unreliable and inconsistent. Appliances should not be left plugged in when not in use. Laptops dshould be unplugged when you're not using them to save them getting strained from surges.
Visitors from USA may need an adapter and a transformer.
A torch is a great help to get you back to your accomodation in the aleys of Stone Town.
A GOOD PAIR OF BOOTS!
Walking around Zanzibar is a fantastic way to see everything, but you get plenty of hazards. Natural ones are the usual rocks, vines, animal droppings, etc. Manmade items like glass and other rubbish make an appearance from time to time. And if that wasn’t enough – the rainy season will make you want those quick dry light hiking boots!