Island with a conscience

If you pack your principles with you when you go travelling, you like to know that the places you choose to stay have a positive effect on their environment and the people who live nearby. If that's you, there are few better places to choose than Zanzibar's remarkable Chumbe island. It would be hard to find anywhere in the world with a lighter carbon footprint. It is both a a blueprint for environmental excellence and for sympathetic design.

Stylish bandas rise up from the island like the Sydney Opera House designed by Robinson Crusoe. Each bungalow squats on a vast water tank where harvested rain water is stored and pumped up to gravity-fed tanks every morning by staff. Showers are simple, and the toilets are compost - releasing sewage into the sea is a no-no, as it encourages algae that block the sunlight from reaching the corals. After using the facilities you simply chuck in a couple of shovelfuls of earthy looking compost, consisting of pieces of wood and old makuti thatch from the roofs of the bandas - a use is found for everything. Ventilation is all natural - the only fans to be found are the handheld, handmade kind.

Rooms feature comfortable swinging day-beds decorated in bright kitenge fabrics of forest greens and ocean blues. Electricity is all solar, as are the torches guests can use to find their way around at night-time, and the hot water in the showers is solar-heated. The kitchen uses a grey water filtration system that sieves off food and fat particles and then cleanses water by filtering it through a natural reed bed.

The island is eminently accessible - it is reached by boat, which leaves from either the beach or jetty at Mbweni Ruins Hotel, just ten minutes to the south of Stone Town. At low tide you have to wade out, first through the mangroves and then through beds of mussels who react to the onslaught of human feet by clamping shut, making a noise like exploding popcorn. If you arrive at low tide, when you land on the island's beach after a 45-minute boat trip, you will clamber through rock pools, teeming with crabs - the leitmotif of this island.

Crabs are everywhere - hermit crabs in aged, moss-encrusted shells scramble enthusiastically over the island's compost pile, devouring anything from rotten tomatoes to potato peelings. Ghost and shore crabs dot around the beaches, and the shy coconut crab, East Africa's biggest crab, can be seen here - although it's nocturnal, it can occasionally be spotted making daytime forays.

Chumbe, started back in 1992, is not particularly cheap - but it is run as a not-for-profit enterprise, and all funds generated from eco-tourism are ploughed into a raft of essential conservation and education projects. Examples include local fishermen, who visit the island and snorkel to gain a deeper understanding of the marine ecosystem, its interconnectedness and the effects of various forms of fishing on Zanzibar's marine life.

According to guides, many fishermen still don't know that coral is alive, and believe it to be a kind of stone that cannot be easily damaged. Work is being done with fishermen to help them to develop alternative sources of income, and to encourage them to abandon destructive styles of fishing, such as using drag nets or dynamite. Schoolchildren are also brought for regular trips here and are taught about the coral reef and its inhabitants in the purpose-designed classroom in the island's education centre. The children are then taken snorkelling to see the real thing. Ferry captains also recently visited the island - ferries from Dar Es Salaam to Zanzibar had been passing too close to the fragile reefs, and so island staff showed them the reefs and what was being put at risk. The entire western side of the island is a marine conservation area, with fishing and diving banned.

This makes for amazing snorkelling for guests and day trippers, with an array of stunning coral reef fish and excellent guides. The reef plays host to at least 200 species of coral and 400 species of fish, and has one of the highest levels of marine biodiversity in East Africa. The sad part of the tale is that staff who have been monitoring the reefs for over a decade are seeing strong evidence of coral bleaching as a result of global warming - this verdict is backed up by staff at Mnemba island to the north-east of Zanzibar.

Both islands are lobbying for more intensive marine monitoring and preservation, but the problem is a worldwide one, and there is a limit to what can be done locally. Beds of sea grass, which provide sanctuary for fish, crustaceans and turtles, and a nursery for their young, are also dying. Of the 58 sea grass species in the world, seven are found off Chumbe.

The interior of the island is also fascinating. Ninety percent of the island is covered by one of the last remaining pristine coral rag forests in Zanzibar - and only one third of that forest is open to visitors, leaving the rest to nature. The island is formed from the skeletal remains of coral reefs and colonies that rose from the sea as sea levels dropped during the Ice Age. There is little fruitful soil, and most of the soil that there is is very salty, with no groundwater. Despite this, a multitude of hardy plant species survive in these adverse conditions.

After the island was born, migratory birds came and dropped seeds from the mainland, and slowly the forest started to emerge. Mangroves thrive, and vast grizzled baobabs. Cactus-like euphorbia rise up from the rocks, and spiky, alien screw palms. On the eastern shores of the island, honeycombed catacombs of dead coral rise jaggedly, interspersed with deep holes and the weird contours of fossilised brain corals.

Chumbe also has a history - the British built a lighthouse there back in 1904, which still stands, and overnight guests can climb the 132 steps to the top for the reward of 360 views around the island, particularly breathtaking at sunset. There is also a mosque, built in 1906 by Indian Muslim lighthouse keepers, which was restored using authentic methods last year and which remains an active mosque, used by staff and Muslim visitors.

While Chumbe is undoubtedly worthy, it's also enjoyable. It has a genuine desert island feel, and guests can explore the forest, go for intertidal walks and regular snorkelling trips, enjoy meals in the refectory-style restaurant, chat with the informative and enthusiastic guides or just relax on the beach beds along the strip of beach in front of the bungalows.

If the island is beyond your budget for an overnight stay, you can visit on a day trip and still see the island's highlights. Daytrippers also get the luxury of a banda for the day to change and relax in. Nonetheless, if you have the money, staying the night gives you the joy of having the island more or less to yourself and a handful of other guests. Romantics can request private dinners on the beach or go for a sail in a local wooden ngalawa boat. Whale watching can also be arranged from mid-July to September.

For the idealist romantic who wants to be cast away with a clean conscience and a happy heart, Chumbe is a top feelgood destination.

See our Chumbe island picture gallery