The Kawanishi H8K[a] is a flying boat used by the Imperial Japanese Navy Air Service during World War II for maritime patrol duties.

The Kawanishi H8K was a large, four-engine aircraft designed for long range and extended endurance on patrols or bombing missions typically flown alone over the ocean.

The robust H8K2 "Emily" flying boat was also fitted with powerful defensive armament, for which Allied pilots had substantial respect wherever this aircraft was encountered in the Pacific theater.

Deepening of the hull, redesigning of the planing bottom and the addition of spray strips under the nose rectified the water handling problems.

Since the target lay out of range for the flying boats, this audacious plan involved a refuelling by submarine at French Frigate Shoals, some 900 km (560 mi) north-west of Hawaii, en route.

Two planes from the Yokohama Kōkūtai (Naval Air Corps)[8] attempted to bomb Pearl Harbor but, due to poor visibility, did not accomplish any significant damage.

The submerged remains of an H8K can be found off the west coast of Saipan, where it is a popular scuba diving attraction known erroneously as the "B-29", or the "Emily".