Indonesia is the world's largest archipelagic state, with more than 18,000 islands and over 7.9 million square kilometres of sea. The marine frontier presents the nation with both economic opportunities and political and strategic challenges. Indonesia has been affected more than most countries in the world by a slow revolution in the management of its waters. Whereas Indonesia's seas were once conceived administratively as little more than the empty space between islands, successive governments have become aware that this view is outmoded. The effective transfer to the seas of regulatory regimes that took shape on land, such as territoriality, has been an enduring challenge to Indonesian governments. This book addresses issues related to maritime boundaries and security, marine safety, inter-island shipping, the development of the archipelagic concept in international law, marine conservation, illegal fishing, and the place of the sea in national and regional identity.