Which piece of equipment might be commonly used during a boarding operation?

During a boarding operation, a portable breathalyzer is commonly used as it serves a crucial role in assessing whether crew members or passengers are operating under the influence of alcohol. The legal limits for blood alcohol concentration are significant in maritime operations, and the breathalyzer provides a quick and efficient means to determine compliance with these regulations.

The focus on ensuring the safety and operational readiness of the vessel makes the breathalyzer a key tool for boarding officers, who must enforce maritime law and ensure the protection of life at sea. The other options, while they may have specific applications in various scenarios, are less routinely employed in the context of a typical boarding operation. For instance, thermal imaging cameras are primarily used for surveillance or search and rescue operations, underwater drones can assist in underwater inspections but may not be practical or necessary during a standard boarding, and deep-sea submersibles are specialized equipment not relevant to immediate boarding assessments.