Which of the following is NOT one of the three elements that comprise jurisdiction?

Jurisdiction, particularly in maritime law, encompasses several key elements that determine a state's authority to enforce laws over a vessel or individuals. The three primary elements are vessel nationality, location, and applicable substantive law.

Vessel nationality refers to the flag under which a vessel is registered, which significantly influences which state's laws apply to the vessel. Location is critical as it defines the geographical scope within which a state can assert its authority, typically influenced by whether the vessel is in territorial seas or on the high seas. Substantive law refers to the specific laws that will be enforced based on the jurisdiction established by vessel nationality and location.

The aspect of "length of time at sea" does not inherently pertain to how jurisdiction is determined. While time at sea may affect practical enforcement or operational considerations, it does not directly define or establish jurisdiction over a vessel or its crew. Thus, it stands apart from the essential elements of jurisdiction.