A group of bottlenose dolphins has been living in the Morbihan Gulf in Brittany for more than thirty years, a rare occurrence in Europe. These dolphins, known for their ability to travel up to 100 kilometers each day, have chosen to remain in the gulf despite having the freedom to move elsewhere. Scientists believe their decision to stay is due to the area's abundant food supply, including pelagic fish that thrive in cold water upwellings in the Mor Braz. The gulf's unique geography also provides a natural shelter, contributing to the dolphins' long-term presence. Each dolphin in the gulf can be individually identified by the unique markings on its dorsal fin, a process that is essential for tracking the population and understanding its behavior. The Morbihan Gulf is home to a relatively small group of about a dozen bottlenose dolphins, which allows researchers to closely monitor and study the individuals over time. This unusual level of interaction between dolphins and humans has turned the area into a living laboratory for scientific research, offering rare insights into dolphin social structures and behaviors. The first systematic records of dolphins in the Morbihan Gulf date back to the 1990s, when researchers realized that the dolphins were not just passing through but living in the area year-round. This discovery changed the understanding of dolphin behavior along the French coast. Today, guided observation tours from the Morbihan Gulf, as well as from nearby towns like Concarneau and Lorient, continue the work of identifying and monitoring the dolphins, contributing to long-term population studies. The stability of the dolphin population depends on maintaining a delicate ecological balance. The Mor Braz, a coastal region between the Morbihan and Belle-Île, is rich in nutrients that support zooplankton and small pelagic fish, which in turn provide a reliable food source for the dolphins. However, this balance is at risk from increasing tourist activity, especially in autumn, as well as noise pollution and changes in prey availability. These challenges highlight the need for continued scientific monitoring to detect early signs of ecological stress and to adjust conservation strategies as needed.