NAVIGATION PLANNING SYSTEM AND NAVIGATION PLANNING METHOD

A navigation planning system of the present invention comprises a processing circuitry configured to acquire planned route information indicating a movable body on the water; acquire movable body information including a position, a moving direction, and a speed of the movable body; acquire obstacle information including each of a position, a moving direction, and a speed of a plurality of obstacles located in the surrounding area of the movable body; calculate a collision risk indicating a risk level of collision between the movable body and the obstacle based on the movable body information and the obstacle information; calculate congestion risk indicating a degree of approaching a plurality of obstacles simultaneously based on each of the collision risk between the movable body and the obstacle; and determine the necessity of evasion by comparing the congestion risk with a threshold value.