Adaptation of bottlenose dolphin, Tursiops truncatus (Montagu, 1821) to the life in the sea include anatomical and physiological changes that happened when mammals moved from land to the sea. The most important adaptations for good swimming are streaming body and development of flippers and fluke. Adaptations for diving include circulatory and respiratory changes. The key changes in circulatory system are development of retia mirabilia, high concentrations of myoglobin, bradycardia, peripheral vasoconstriction and low metabolic rate during dive. The key changes in respiratory system are highly vascularized alveoli, the lungs modified to allow to collapse and a blowhole at dorsal side of the head that opens actively and closes passively. Digestive system is very long. A stomach resembles that of ruminants and enzymatic digestion in it has a great significance. Hearing is the most developed sensory system of the bottlenose dolphin. The other sensory systems are not as developed as they are in terrestrial mammals but that is compensated with echolocation capabilities. Vocalization of the bottlenose dolphin is easy recognizable and sounds like a whistle. Every individual and every population has its own whistle contour. The main role in thermoregulation play blubber and heat-conserving vascular countcurrent systems and also reduced surface-to-volume ratio. The kidneys produce hypertonic (highly concentrated) urine as adaptation to hypertonic environment. Bottlenose dolphins are known for their complex social structure, tight group bonds and caring for their offspring. Promiscuity is important for genetic biodiversity. Delayed implantation and long period that baby dolphin spends with its mother are crucial for species conservation.