Dolphins are intelligent sea animals. They live in groups and communicate with each other using special sounds. Scientists believe that dolphins have their own language. They are friendly to people and often swim near ships. Some dolphins are trained to help humans, for example in rescue operations. However, life in the wild is difficult for them. Water pollution and plastic waste are dangerous for marine animals. In some regions, dolphins are even hunted, which is considered a crime against nature. Fortunately, international organisations are trying to protect these wonderful animals. Nowadays, dolphins are often used in scientific research to study communication and intelligence.