What is Mariner?

Legal Definition
One whose occupation is to navigate vessels on the sea. Vide Seamen Shipping articles.

2. By act of congress, 1 Story, Laws of U. S., ch. 56, s. 4, p. 109, it is provided, that no sum exceeding one dollar shall be recovered from any seaman or mariner (in the merchant service,) by any person, for any debt contracted during the time such seaman or mariner shall actually belong to any ship or vessel, until the voyage for which such seaman or mariner engaged, shall be ended.
-- Bouviers Law Dictionary
Legal Definition
A seaman or sailor; one engaged in navigating vessels upon the sea.
-- Black's Law Dictionary
Legal Definition
Anyone, except the master, who aids in the navigation of a ship.
-- Ballentine's Law Dictionary