What is the definition of innocent passage?

Innocent passage refers to the right of a vessel to traverse through the territorial sea of a coastal state as long as it does so in a manner that is not prejudicial to the peace, good order, or security of the coastal state's territorial waters. This includes navigating through these waters without engaging in any activities that could be deemed threatening or harmful, such as military maneuvers or exercises.

This definition underscores the importance of maintaining peaceful transit, emphasizing that while vessels have the right to pass through, they must do so without engaging in military activities or actions that could disturb the coastal state. This principle is especially important in international law, as it balances the rights of vessels to navigate with the rights of states to control their territorial waters.

The other options presented do not accurately capture the essence of innocent passage. For instance, transiting territorial waters without stopping could imply a lack of engagement but doesn't address the requirement of not undertaking military actions. Entering a nation's airspace without permission and surfacing submarines in territorial waters pertain to more complex issues of sovereignty and military operations, which are not covered under the definition of innocent passage. Thus, the correct choice encapsulates the essential requirement of peaceful navigation through a state's territorial sea.