Path planning for an underwater vehicle can be formulated as a multiobjective optimization problem, which can be solved by modern heuristic techniques. For assessment of a trajectory, three crucial criteria are used: a total length of a path, a smoothness of a trajectory, and a measure of safety. A multiobjective evolutionary algorithm for finding Pareto-optimal solutions is proposed. Then, the underwater vehicle and navigation in three dimensions is considered. Some results of numerical simulations are presented.