Internal waters, the territorial sea, international straits and archipelagic waters are marine spaces under the territorial sovereignty of the coastal State. However, the use of the marine environment for sea communication necessitates the freedom of navigation through those spaces. Consequently, marine spaces under territorial sovereignty are part of the territory of the coastal State and the highway for sea communication at the same time. The dual nature of marine spaces gives rise to the fundamental question of how it is possible to reconcile the territorial sovereignty of the coastal State and the freedom of navigation. With that question as a backdrop, this chapter will examine the following issues in particular: (1) the coastal States jurisdiction over foreign vessels in internal waters, (2) refuge for ships in distress, (3) the right of innocent passage through the territorial sea, (4) the legal regime of international straits, (5) the legal regime of archipelagic waters, and (6) the differences between the right of innocent passage, the right of transit passage and the right of archipelagic sea lane passage.