Sea stacks are tall, vertical columns of rock that rise from the ocean, formed by the erosion of coastal cliffs. Over time, waves and weather wear away the softer rock, leaving behind these isolated formations. They can vary in size and shape, often standing majestically against the backdrop of the sea. These natural structures are commonly found in coastal areas around the world, such as the Great Ocean Road in Australia and the Giant's Causeway in Northern Ireland. Sea stacks are popular among photographers and nature enthusiasts, offering stunning views and unique ecosystems for marine life.