This sound of lightning striking the ocean was recorded underwater in the Gulf of Mexico.
Sound courtesy of Henry Bass, Roy Arnold and Anthony Atchley, National Center for Physical Acoustics. Released under Creative Commons License, non-commercial attribution.
Lightning strikes the coastal ocean at a rate of about 2 strikes per square kilometer per year. Lightning in the open ocean is rare. Most people are very familiar with lightning because lightning strikes the land much more often than the ocean. In the arctic and antarctic there is very little lightning.