Freedom of the seas is a principle in the law of the sea. It stresses freedom to navigate the oceans. It also disapproves of war fought in water. The freedom is to be breached only in a necessary international agreement.
Freedom of the Seas, World War II US poster
Law of the sea is a body of international law governing the rights and duties of states in maritime environments. It concerns matters such as navigational rights, sea mineral claims, and coastal waters jurisdiction.
Mare Liberum (1609) by Hugo Grotius is one of the earliest works on law of the sea.