Which of the following defines "Maritime"?

The term "Maritime" refers specifically to anything that is related to the sea. This encompasses a broad range of topics, including shipping, naval operations, marine navigation, and oceanography. Maritime activities play a crucial role in global trade and military operations, as the sea serves as a major route for transporting goods and services. Understanding maritime concepts is essential for those involved in naval and nautical fields, as well as for economic and environmental studies related to ocean use and preservation.

The other options focus on distinct areas that fall outside the definition of "Maritime." For instance, references to river navigation would pertain to inland waterway transport, while air travel and aviation relate to the atmosphere. Land-based military operations do not involve sea activities, which further confirms that only the option concerning the sea accurately captures the essence of the term "Maritime."