Final answer:
The country with the Caribbean Sea to the south, the Atlantic Ocean to the north, and separated from Puerto Rico by the Mona Passage, is the Dominican Republic.
Step-by-step explanation:
The country that has the Caribbean Sea on its southern coast, the Atlantic Ocean to the north, and is separated from Puerto Rico by the Mona Passage is the Dominican Republic. The Dominican Republic shares the island of Hispaniola with Haiti, which is part of the Greater Antilles.
This region, inclusive of the Dominican Republic, has seen significant European influence during the colonial era and is now known for its vibrant tourism industry, especially catering to cruise ships.