Usually, the only reason whales come to the surface is to breathe. Humpbacks are capable of holding their breath for 45 minutes or longer, however, dives of this length are unusual.
Whales have very efficient lungs.
The size of a humpback's lungs also assists its breathing capacity. Special Blood Humpback whales also have a substance in their bloodstream called myohemoglobin. Myohemoglobin aids in holding oxygen, then delivers it to whatever part of the body needs it the most. They also have an oxygen holding substance in their muscle tissue called myoglobin. In fact, whale muscle tissue is a deep red, almost purple color because it holds such an amazing amount of oxygen.