What is the least depth on the approach to Terminal 20 in the area south of Terminal 18-4, Seattle?

The correct choice is 36' because this figure accurately represents the minimum depth on the approach to Terminal 20 in the specified area south of Terminal 18-4 in Seattle. Understanding the navigation and operational requirements for marine approaches is crucial for ensuring safe and efficient vessel maneuvering.

In the context of marine operations, maintaining a sufficient water depth is essential to accommodate the draft of the vessels expected to use the terminal. The designated depth indicates that vessels can safely transit without risk of grounding, making it a critical factor in planning and scheduling activities related to maritime logistics.

Depth measurements are established through surveys and navigational studies, which take into account local topography, sediment deposition, and tidal variations. The value of 36' reflects careful assessment and ensures that vessels of various sizes can reliably access and use the terminal, thereby supporting efficient port operations and traffic management.