Fjords are deep, narrow inlets of the sea that are surrounded by steep cliffs or mountains. They are formed by the glacial erosion of valleys, which creates a U-shaped profile. When glaciers melt, seawater fills these valleys, resulting in the stunning landscapes often seen in places like Norway and New Zealand. Fjords can vary in size and depth, with some reaching depths of over 1,000 meters. They are typically characterized by their calm waters and dramatic scenery, making them popular destinations for tourists and outdoor enthusiasts. Wildlife, including seals and various bird species, often thrives in these unique ecosystems.