Which of the following is defined as a small boat commonly used for coastal navigation and fishing?

The term referred to in the context of a small boat commonly used for coastal navigation and fishing is a skiff. A skiff is characterized by its light weight and shallow draft, making it ideal for navigating shallow waters, beaches, and coastal areas. It is often used by fishermen for both commercial and recreational purposes, allowing for easy handling and maneuverability.

A yawl, while also a type of boat, is typically larger and is characterized by having two masts, with the smaller aft mast being located behind the rudder. Yawls are generally used for sailing rather than fishing specifically.

A catamaran, on the other hand, is identified by having two hulls and is designed for stability and speed, often used for leisure activities and sometimes for fishing, but not commonly described as a small boat.

Lastly, a submarine is a watercraft capable of independent operation underwater and is not a type of small boat used for coastal navigation.

In conclusion, skiffs are the most suitable option for the defined purpose, as they are lightweight and specifically tailored for activities like coastal fishing and navigation.