Travel down the east coast of Zanzibar on board an Arab dhow, and the spice island seems not to have changed for centuries. A row of white surf, open sand and coconut palms marks the shoreline.
For miles, there is no intrusion from anything man-made, save for the triangular white sails of other dhows, so graceful and slender that they seem entirely as nature intended.
From time to time, the thatched, conical roofs of a handful of relatively small hotels appear among the palm trees. But the Indian Ocean's turquoise waters still lap a largely undeveloped coast.
This may not be true for much longer. Prodded by the central authorities in Tanzania, Zanzibar's semi-autonomous government is promoting the development of big hotels along the eastern shore.
The idea is to change the focus of the island's tourism. At present, Zanzibar benefits from a high-value, low-volume model where most visitors come to the spice island after a safari in Tanzania's national parks. They stay for an average of five nights in a few, comparatively small hotels, often directly overlooking the sea.
But Amani Abeid Karume, the president of Zanzibar, wants to change this. The idea is to make Zanzibar a mass destination in its own right – independent of "bush and beach" visitors who go on safari first. This means lower prices, more hotel beds, more tourists and, perhaps inevitably, an end to the undeveloped beauty of the east coast.
"Sadly, the government of Zanzibar has this idea that they have to be like Kenya and Mauritius and they need big investors to build big hotels," says one local operator. "Zanzibar might end up being a cheap destination for mass tourism."
If so, small retreats, like Ras Nungwi Beach Hotel on the island's northern peninsula, will become rare exceptions. Set on a perfect tropical beach, where the afternoon tide brings turquoise water lapping against honeycombed rocks and white sand, Ras Nungwi has only 32 rooms.
Most are found in thatched rondavels, often directly overlooking the ocean. Ras Nungwi was built before a new regulation came into force, specifying that all hotel rooms must be at least 250ft from the high-tide mark.
If you stay in the Ocean Suite, you will have a small beach to yourself, complete with your own two-storey house with more than 2,000 sq ft of living space.
Elsewhere in Zanzibar, seaweed and cloudy waters can make the beach disappointing. At Ras Nungwi, however, the sand could scarcely be finer nor the water clearer.
"There is a big turnaround of oceanic currents here, which gives us our clear water," explains Chris Goodwin, the general manager.
If Zanzibar eventually succumbs to the mass tourism model, small and intimate havens such as Ras Nungwi will become rarer.