When Mount Liamuiga erupted about 1,800 years ago, much of the lava flowed toward the island’s northeast coastline. Imagine the plumes of gas and steam when the hot magma met the Atlantic Ocean. Relentless waves along the windward side then carved the basalt into an array of sea stacks stretching for almost two miles. This intriguing sculpture garden of nature is called Black Rocks. Viewing this geological phenomenon is free.