Final answer:
Mt. Diablotins National Park and Morne Trois Pitons National Park are located in Dominica, a country known for its impressive volcanic features and biodiversity, not to be confused with various U.S. parks such as Yellowstone or Hawaii Volcanoes National Park.
Step-by-step explanation:
The country that hosts both Mt. Diablotins National Park and Morne Trois Pitons National Park is Dominica. The island of Dominica stands out with its lush natural parks and is known for its impressive volcanic features. Unlike the listed parks in the information provided such as Hawaii Volcanoes National Park, Devils Tower National Monument, Yellowstone National Park, Crater Lake National Park, Pinnacles National Park, Mount St. Helens National Volcanic Monument, and Lava Beds National Monument, which are in the United States, Mt. Diablotins and Morne Trois Pitons National Parks are in a Caribbean country renowned for its natural beauty and biodiversity. Morne Trois Pitons National Park, in particular, is a UNESCO World Heritage Site, famous for its lush landscapes and the boiling lake that is a flooded fumarole.