The municipal flag of Puerto Plata can be seen flying alongside the Dominican Republic national flag in several photographs online at http://www.skyscrapercity.com/showthread.php?p=138300919. The flag features the shield of the municipal coat of arms centered on a white field. The coat of arms shows on a white shield a green mountain above three wavy blue lines, representing Columbus' Monte de Plata overlooking the ocean. The mountain is flanked by a black capital "F" toward the hoist and a black capital "Y" toward the fly, both topped with gold (yellow) crowns, representing the Spanish monarchs at the time of the city's founding - Ferdinand and Ysabel (Isabella). Randy Young, 4 April 2017
The city of San Felipe de Puerto Plata, also known as simply Puerto Plata, is the capital of Puerto Plata Province in the Dominican Republic. It is the ninth largest city in the country and one of the primary commercial ports. Founded sometime between 1496 and 1506 (historical records conflict on the year of the city's founding), the port derives its name from the nearby mountain Isabel de Torres, which Christopher Columbus referred to in 1493 as "Monte de Plata" due to the perpetual fog at the top giving it a silvery appearance. In the mid-1500s, Puerto Plata became something of a pirate haven in the Caribbean, and was ordered destroyed by Spain's King Phillip III in 1605 in an attempt to prevent the English forces staging there against Spanish colonies in the Caribbean. The city was destroyed again in 1863 during the Dominican Restoration War, which saw Dominican guerrilla forces successfully force the withdraw of Spanish military forces and the restoration of Dominican independence.
Source: Wikipedia article Randy Young, 4 April 2017