At the surface they generally take two to five breaths at five to ten second intervals before another dive. They make approximately three to five short dives, each lasting 10 to 35 seconds. These are followed by longer dives lasting about one to four minutes. Dives up to 10 minutes and longer have been seen, with the longest dive observed in the ocean lasting 12 minutes. Under experimental conditions, killer whales have made dives lasting as long as 15 minutes.
All marine mammals have special physiological adaptations when they dive.
These adaptations enable a killer whale to conserve oxygen while under water. A killer whale's heart rate can slow from 60 beats to 30 beats per minute while diving. Marine mammals have a higher concentration of the oxygen-binding protein myoglobin in the muscles. Myoglobin stores oxygen and helps prevent muscle oxygen deficiency. These combined adaptations allow a killer whale to conserve oxygen during a dive.