All visitors require a passport, valid for the duration of their stay. Visitors may obtain visas upon arriving at Zanzibar International Airport. Other points in Tanzania currently offering visa on entry are Dar es Salaam and Kilimanjaro International Airports, and Namanga on the road border between Tanzania and Kenya. Nationals of some countries do not require visas, so it is advisable to check with your nearest Tanzanian Embassy, High Commission or Consulate prior to visiting.
Zanzibar is largely a Muslim community. Although they are used to Western ways, you should try to be respectful. This means:
Women and men should make an effort to cover their legs and arms.
It is regarded as disrespectful to show public affection.
Be discreet when drinking alcohol.
During Ramadan -- the month of fasting -- travelers should avoid eating and drinking during the daytime. Also, be sure not to smoke in front of people, nor chew gum, and it is polite to avoid talking about the nice lunch you had.