WHAT worldwide industry outstrips automobiles, petroleum and weaponry, making up 11 per cent of the world's Gross Domestic Product? The answer is tourism. Locally tourism is also a big industry, with estimates that it will be Hong Kong's biggest foreign currency earner in three to four years' time, contributing at least HK$70 billion a year. With such rapid growth, tourism has the potential to make a major impact on the economy and the environment - all those plane journeys, hotel and resort developments and the opening up of wilderness areas can cause irreversible damage. However, tourism does not have to have a detrimental impact and can actually be a positive thing for the environment, if approached sensitively. Tourist dollars can be used to promote and protect areas of conservation value, provided the money goes back to the local community. Many scenic wonders and areas of outstanding natural beauty are now major tourist attractions, and the economic value given to these areas can help to prevent their destruction. Eco-tourism is defined as 'responsible travel' to natural areas which conserves the environment and sustains the well-being of local people. It is the fastest growing segment of the tourism industry and could be more than just a buzz-word in Hong Kong. To the surprise of most visitors, Hong Kong's natural attractions are extensive - ranging from the beautiful beaches of Sai Kung to the international bird-watching area at Mai Po and the rugged mountain scenery of Lantau. Friends of the Earth (FoE) believes Hong Kong has many natural areas, particularly along the coastline, that are beautiful, accessible and with many interesting features. These are seldom visited by locals or visitors. However, the threats to our coastal areas are worrying. Reclamation, pollution and inappropriate development are rapidly degrading our natural coastline. In the last six years, over 18 km of natural coastline has been lost in North Lantau alone, including the destruction of the islands of Chek Lap Kok and the Brothers, due to the airport core projects. More coastline is under threat, including Green Island and the Yung Shue Wan Bay. What are we doing? Not only are we destroying some fine coastal scenery and polluting beautiful beaches, we are filling in fish nursery areas and destroying marine habitat, which will have an impact on the entire marine ecosystem. Urban development has erased the natural coastline of many areas, and together with pollution, is threatening the attractiveness to visitors. FoE has recently produced a coastal guide to Lamma Island, the first in a series of guides sponsored by the tourist industry to promote Hong Kong's natural areas, while illustrating the threats that they are facing. The guides were devised by FoE's volunteer Water Action Group, who were inspired by the coastline and wanted to promote the ecological, cultural, historical and archaeological heritage of Hong Kong's coastline to locals and visitors alike. FoE believes we should promote the green side of Hong Kong, while alerting the community to the need to protect these areas for economic as well as ecological reasons. FoE is currently working on the second guide in the series on Lantau Island, and hopes eventually to cover the whole of the territory so everyone can explore the coastline and discover some beautiful and important parts of our natural heritage. The guide will be sent to all secondary schools. You can also get copies from FoE and the Hong Kong Tourist Association. All proceeds will be used for producing further guides. Friends of the Earth is a local environmental organisation. For more information, call 2528 5588.