The Americas is surrounded by water so the coastline is vast. To the east is the Atlantic Ocean and on the west is the Pacific. The north is bounded by the Arctic Ocean and the south by the Southern Ocean. Between Alaska and the USSR is the Bering Sea and between the USA and the top of South America lies the Caribbean Sea. The second largest coral reef system on Earth, the Mesoamerican Barrier Reef System lies in the Caribbean. Canada has the longest coastline of any country in the world due to its many large islands and irregular coastline.