Wanderlust World Wanderlust World Under the United Nations Convention on the Law of the Sea (UNCLOS), the maximum breadth of a coastal state's territorial sea is 12 nautical miles (nm) measured from the baseline—typically the mean low-water line. This limit is widely accepted in international law, though a handful of nations have asserted claims extending beyond 12 nm, a practice that lacks universal recognition.
The territorial sea is considered part of a state's sovereign territory. The coastal state exercises full jurisdiction over these waters, including the airspace above, the seabed, and the subsoil. This sovereignty is subject to the right of innocent passage, which allows foreign vessels to transit through territorial waters provided they comply with the coastal state's laws and regulations and do not engage in activities prejudicial to the peace, good order, or security of the coastal state.
The baseline from which the territorial sea is measured is normally the low-water line along the coast as marked on large-scale charts officially recognized by the coastal state. In cases of deeply indented coastlines or fringes of islands, straight baselines may be drawn between appropriate points. The 12-nm limit applies from these baselines outward.
While UNCLOS provides a clear framework, disputes persist over excessive maritime claims, particularly in strategically sensitive regions. The convention also establishes contiguous zones (up to 24 nm), exclusive economic zones (up to 200 nm), and continental shelf rights, each with distinct legal regimes. Understanding these zones is essential for maritime security, resource management, and international navigation.