The Celtic Sea is an area of the Atlantic Ocean off the south coast of Ireland, bounded to the east by Saint George's Channel and the English Channel. It gets its name from the Celtic heritage of the lands that surround it. The sea sits on the European continental shelf, making it relatively shallow compared to the open Atlantic. Geologically, its seabed was shaped by the advance and retreat of glaciers during the last Ice Age, which left behind large deposits of sand and gravel. The Celtic Sea is an incredibly rich fishing ground and also hosts significant gas fields, such as the Kinsale Head gas field off the Irish coast. It is also an important area for marine conservation, serving as a habitat for several species of whales, dolphins, and the grey seal. The sea's weather is notoriously unpredictable, often characterized by heavy swells and Atlantic depressions.