Bears can live in practically every habitat on earth, from tropical jungles to the Arctic Ocean. Wherever they occur, they are capable of surviving extreme conditions and extracting the highest quality food. Detailing the latest research, Chris Packham explores the specialised adaptations that have enabled bears to thrive, including how a polar bear's hollow fur allows it to feed throughout the gruelling Arctic winter, whilst a state of 'walking hibernation' sees them through the summer months.