Is Buoyant Force a Conservative Force?

For an object that is fully submerged the buoyant force is constant (in both magnitude and direction) exactly as the usual "near the surface of the Earth" approximation to gravity. That part is clearly conservative.

Which forces are conservative?

The term conservative force comes from the fact that when a conservative force exists, it conserves mechanical energy. The most familiar conservative forces are gravity, the electric force (in a time-independent magnetic field, see Faraday's law), and spring force.

Is the spring force a conservative force?

If the work done by a force depends only on initial and final positions, not on the path between them, the force is called a conservative force. ... “Spring force” is another conservative force.