This study investigates tourism, diving and the environment on the island of Koh Tao in southern Thailand. The "tourism landscape" and dive sites are examined as common pool resource dilemmas with problems of overuse and environmental degradation. Collective efforts to deal with the environmental problem have been frustrated due to social heterogeneity among community members who differ in terms of nationality, culture, norms, interests, power and environmental values. Two paradoxes characterize the situation on Koh Tao. The first is typical of tourist destinations around the world, in which the features that attract the tourists, such as an "untouched" environment, are destroyed by the very presence of those tourists. The second paradox is that the development of dive tourism has relied on a symbiotic relationship between Thai entrepreneurs and skilled Western expatriates, yet it is this very relationship that is obstructing efforts toward sustaining the industry.