The family Gaviidae, within the order Gaviiformes, comprises the loons, a group of aquatic birds known for their excellent diving abilities and striking vocalizations. Loons are adapted for life in freshwater lakes and coastal waters of the Northern Hemisphere, possessing streamlined bodies, strong webbed feet set far back on the body, and sharp, pointed bills for catching fish. They have elaborate courtship calls and are often monogamous, with both parents participating in raising young. Loons typically migrate seasonally between breeding lakes and coastal wintering grounds, and their presence is considered an indicator of healthy aquatic ecosystems due to their reliance on clear, unpolluted waters.