My partner and I were in Zanzibar this month. Thought that I'd provide a more recent update on expected taxi costs for other travellers.
Airport to Stonetown: 15,000 Tanzanian Shillings or approx 7 USD (bargaining required). They have an official looking price list that indicates 10 USD/20,000 TZS. Waiting taxi drivers will try to convince you that it's a fixed price but you can negotiate.
Stonetown to Pongwe Beach: 60,000 TZS or approx 30 USD. Our hotel charges 50 USD and other taxi services we contacted charge 40 USD.
Pongwe Beach to Ferry Terminal: 60,000 TZS
We used an excellent taxi driver for transfer to/from Pongwe whom we would highly recommend. We felt his price was very reasonable. He was a safe driver, friendly, reliable and has a clean and air conditioned van. He even provided us with bottled water which was a nice bonus!
Khamis Omar Yahya +255 773 169577 or +255 712 369398 or email@example.com