Submarine islands are underwater landforms that rise above the surrounding sea floor but do not reach the water's surface. They are typically formed by volcanic activity, sediment accumulation, or tectonic movements. These islands can vary in size and shape, and they often support unique ecosystems due to their isolation. Many submarine islands are found in oceanic regions, such as the Hawaiian Islands or the Galápagos Islands. They can serve as important habitats for marine life and may influence ocean currents and weather patterns. Some submarine islands are also studied for their geological significance and potential resources.