Final answer:
Cocos Island is owned by Costa Rica and is located 342 miles off the Pacific coast in the northeastern Pacific Ocean.
Step-by-step explanation:
The country that has Cocos Island 342 miles off the Pacific coast is Costa Rica. Costa Rica's Cocos Island is a renowned natural UNESCO World Heritage site, widely known for its ocean biodiversity, including sharks, rays, dolphins, and other marine life. It serves as a critical point of interest for both scientific research and ecotourism.
Situated in the northeastern Pacific Ocean, the island is not to be confused with the Cocos (Keeling) Islands in the Indian Ocean, which are a territory of Australia, or the territory of Guam, a US possession in Micronesia which is also in the Pacific but is well known for its military installations and strategic importance during World War II.