The Pathfinder, or The Inland Sea is an historical novel by James Fenimore Cooper first published in 1840. It is the fourth novel Cooper wrote featuring Natty Bumppo, his fictitious frontier hero, and is considered as forming the third chronological episode of the Leatherstocking Tales. The inland sea of the title is Lake Ontario.The Pathfinder was written 13 years after Natty Bumppo had ended his career in The Prairie. Cooper had questioned the wisdom of reviving this hero, and he was at the time engaged in fierce litigations with newspapers. The adventures of the plot on the water take authority from the fact that Cooper had as midshipman actually seen service on Lake Ontario.