Nusantara, the vast archipelago of Southeast Asia, has historically been defined by its intricate relationship with the sea. This article explores the profound maritime legacy of the region, tracing its evolution from the era of Hindu-Buddhist kingdoms through to the pre-colonial period. It examines how seafaring traditions, strategic trade routes, and powerful maritime empires shaped the political, economic, and cultural landscape of Nusantara. By analyzing the pivotal role of the sea as a unifier and a conduit for exchange, this study highlights the enduring significance of maritime history in understanding the identity and development of the archipelago before the advent of European colonial powers.