Nungwi sits at the northern tip of Unguja, and is arguably Zanzibar's finest beach — not just for the colour of the water (a deep turquoise that bleaches white closer to shore) but because the northern tip largely avoids the tidal extremes that plague the east coast. You can swim comfortably at any time of day, which the more famous east coast beaches cannot always offer.
The village behind the beach has grown substantially with tourism but retains a working character. Dhow-builders still set up on the beach, and you can watch traditional wooden vessels — some destined for the high seas between Zanzibar, Dar es Salaam, and the Arabian Peninsula — being shaped by hand using adzes and hand tools. The natural tidal pool (the Nungwi Aquarium) near the lighthouse is home to captive green turtles, and it costs a small fee to swim with them. It is one of Zanzibar's more touristy experiences but the turtles are genuine and the setting is beautiful.
Water sports are available from multiple operators on the beach: snorkelling trips to nearby reefs, scuba diving with PADI-certified centres, and sunset dhow cruises. In the evenings, the beach bars north of the main fishing village draw a mix of backpackers and resort guests.