What equipment is essential for underwater navigation?

Underwater navigation relies heavily on specific tools that aid divers in determining their direction and position while submerged. A compass is essential for this task because it helps divers identify their heading and maintain a specific course. By using a compass, divers can navigate effectively, especially when visibility is limited or when traversing featureless underwater environments.

While dive computers are valuable for monitoring dive parameters and ensuring safety throughout the dive, they are not primarily designed for navigation purposes. Drysuits provide thermal protection and are unrelated to navigation, serving more to keep divers warm in cold water. Surface marker buoys are useful for indicating the diver’s position at the surface but do not assist with navigation underwater.

Therefore, the compass is the critical piece of equipment that allows divers to orient themselves and navigate accurately underwater, making it the correct choice for this question.