The term “straits” designates a narrow maritime passage between two land masses that links two seas. Like an isthmus or a canal, it represents not only a strategic axis but also a structural axis in global organization. This unique and complex zone of land-to-sea interface has become a major factor in the twentieth century, as coastal nations have exercised their political will by enlarging their sphere farther and farther out to sea and by nationalizing the seaways. Although the Conference of Montego Bay in 1982 put an end to decades of tensions and even conflicts by establishing rules to regulate this appropriation and to delimit the maritime borders, international straits remain insufficiently defined geographical areas. Often considered solely as a narrowing of the maritime region in which navigating conditions frequently become difficult, straits are rarely considered as separate territories structured by longitudinal as well as latitudinal flow (Picouet and Renard 2002).

The originality of the Straits of Malacca is precisely the fact that it is both a zone of major exchange and transit in international commerce, in which the nations situated along its coasts have always been deeply integrated, and a region in itself, shaped, despite the borders that separate the opposing coasts, by a tight web of commercial and cultural relations between the two coasts (Fau 2003a, p. 34). A multi-level approach is necessary in order to understand the functioning of these straits, which are given structure both by the latitudinal flow, for the most part transoceanic, and by the transversal flow linking the two coasts.

This multiple reality of the Straits of Malacca will be studied in this chapter under the angle of an analysis of the maritime shipping networks and of the different levels of organization in the port systems. In order to understand the articulation of the different maritime flows and their impact on the spatial organization of the coasts, the straits are considered successively as a corridor of intense global maritime circulation, as a natural border between Malaysia and Indonesia, and lastly as an inland sea in which the local shipping flow has been given a new dynamic by the opening of the borders.