What type of vessel must keep clear of all other vessels?

A seaplane must keep clear of all other vessels primarily because it operates above the water and is not subject to the same navigational rules that apply to vessels on the water. The nature of its operation means it is more like an aircraft when it comes to maneuvering and maintaining safe distances from other vessels.

In contrast, fishing vessels, power-driven vessels, and vessels under command have specific requirements and rights under the navigation rules. For instance, fishing vessels often have to keep clear of vessels engaged in other maritime activities unless they are actively fishing themselves. Power-driven vessels, such as those with engines, have obligations to give way or take action based on their maneuverability and the situation. A vessel under command, which is unable to maneuver due to exceptional circumstances, may have the right of way, requiring other vessels to take care to avoid collisions with it. Thus, the unique status of the seaplane in maritime operations clarifies why it needs to keep clear of all other vessels.