Rapids are sections of a river where the water flows quickly and turbulently over rocks and other obstacles. This fast-moving water creates waves and white foam, making it exciting for adventurers. People often enjoy activities like white-water rafting or kayaking in these areas, as the thrill of navigating through the rapids can be both challenging and fun. The formation of rapids usually occurs in steep or rocky riverbeds, where the water's speed increases due to the drop in elevation. These natural features are important for ecosystems, as they provide habitats for various aquatic life, including fish like trout and salmon.