Introduction Today, on World Dolphin Day, we celebrate these intelligent, social, and fascinating marine mammals. Dolphins have captured the hearts and imaginations of people worldwide with their playful antics, strong family bonds, and apparent smiles. However, many dolphin species face serious threats to their survival, with some already extinct and others on the brink of extinction. This comprehensive article will explore the world of dolphins, delving into their habitats, intelligence, and the challenges they face, while highlighting the endangered species and those recently lost forever. Dolphin Habitats and Diversity Dolphins are found in a wide range of aquatic habitats, from tropical and temperate oceans to rivers and lakes. While most dolphin species are marine, there are also several species that live in freshwater environments. These include the Amazon river dolphin, the Indus river dolphin, the Ganges river dolphin, and the Irrawaddy dolphin . The Amazon river dolphin, also