You can get Zanzibar by airplane which is about 15 minutes  from Dar es Salaam Mwl J.K.NYERERE international airport.And also you can take ferry boat from Dar es salaam which takes 2 hours to arrive, Ferry goes 4 times  a  day between 7am to 16hrs  in both directions ( Dar – Zanzibar, and Zanzibar -Zanzibar).