16. (6 points) A merchant ship sailing in the Somali Sea discovers a pirate ship 50 nautical miles away in the direction of 60° north of west. The merchant ship then calls for help from an escort ship, which is 50 nautical miles away in the direction of 60° south of west. At this moment, the escort ship is in the exact 
（fill in East, West, South, North）direction $\qquad$ nautical miles away from the pirate ship.
【Analysis】Based on the conditions of the problem, draw a schematic diagram as shown: The positions of the pirate ship, merchant ship, and escort ship form an equilateral triangle, with the escort ship located 50 nautical miles due south of the pirate ship.

【Solution】Solution: Since the positions of the pirate ship, merchant ship, and escort ship form an equilateral triangle, the escort ship is located 50 nautical miles due south of the pirate ship.
Therefore, the answer is: South, 50.
【Comment】The key to solving this problem is to understand that the positions of the pirate ship, merchant ship, and escort ship form an equilateral triangle, thus making the solution straightforward.