Scientists have, for the first time, recorded the heart activity of a fin whale, one of the largest animals on Earth. Utilizing a new suction-cup ECG device attached to the whale’s back during a Mediterranean Sea mission in August 2025, researchers observed dramatic changes in heart rate. The whale’s heart rate slowed to as few as five beats per minute during deep dives, compared to 25 beats per minute when surfacing to breathe. This extreme variation in heart rate allows the whale to conserve oxygen during extended dives, lasting up to twenty minutes. The five-hour ECG recording provides valuable insight into whale physiology, revealing their mastery of apnea. This breakthrough promises advancements in cetacean research and improved conservation efforts in the face of human-caused disturbances.