What type of waters does the term 'Territorial Seas' refer to?

The term 'Territorial Seas' refers specifically to waters adjacent to a nation's coastline over which that country exercises sovereignty. For the United States, this generally extends 12 nautical miles (NM) from the baseline of its coast, allowing the country to regulate various activities such as fishing, navigation, and resource extraction in these waters. This sovereignty means that the coastal state has rights to enforce its laws and regulations, as well as to control the passage of foreign vessels through these waters, although innocent passage is typically allowed.

The other options do not accurately describe territorial seas. Coastal harbors are part of internal waters and do not represent the full scope of territorial seas. Open ocean beyond 12 nautical miles does not fall under the domain of any single country but instead is considered international waters. Similarly, international waters, while freely accessible to all vessels, lie beyond the limits of territorial seas and do not imply any exercise of sovereignty by a coastal nation.