According to the World Tourism Organisation, in 2000, 698 million people travelled to a foreign country and spent over US$ 478 billion. Passenger transport combined with international tourism revenues currently total more than US$ 575 billion. This makes tourism the world's number one export earner, ahead of automotive products, chemicals, petroleum and food. Though leisure activities are now the world s biggest industry, tourism is usually poorly managed from an environmental perspective. Development often takes place as near to favourite spots as possible, no matter what the impact, while visitors usually produce more sewage and garbage than local people do. In addition, though tourism can encourage the conservation of countries natural environments it can be questioned whether increasingly popular maritime tourism brings countries, especially developing countries and small island states, enough receipts to meet the costs of maintaining their ecosystems. A UNEP study on managing the impact of tourism on small islands concluded: Overall, tourism tends to be a mixed blessing in its benefits and impacts on the island environment. If it is allowed to grow unplanned, it can have serious social and environmental impacts while providing little real economic benefit. If developed with care, it can bring many advantages to small island communities with few other resources.