The Pacific Ocean was the largest theater of military operations in history. Covering nearly one-third of Planet Earth, no bigger arena is possible. And even discounting more than half of that surface, which saw no combat action, leaves about 30 million square miles.
Naval combat did not lend itself to prolonged engagements as were common in land battles. Opposing fleets clashed over one or two days, and generally the issue was resolved. Unlike aircraft and armored vehicles, warships required months or years to build, and their losses were not easily replaced. But inserting the airplane into the mix changed the combat dynamics, resulting in Pacific actions ranging from one day to six months.