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The foraging ecology of King Penguins (Aptenodytes patagonicus) at Possession Island, Crozet Archipelago, was studied between January and March 1993 and between February and March 1994. Diving activity and position of the birds were determined via externally attached logging units. Feeding behavior was detected using stomach temperature sensors. All calculated positions of the birds occurred south of Possession Island. The area most frequented was situated 250 km south of the island (48.5 ° S), where birds stayed for 40 h during a foraging trip, on average. The overall swim speed differed with time into the foraging trip, being lowest during the central part and highest (10 km/h) during the last night at sea, when birds were returning to the colony. Diving activities showed a clear diurnal pattern, with maximum dive depth being dependent on ambient light levels. During the night, only shallow dives 85% of the feeding events occurred during daylight and at twilight. Mean food mass ingested was calculated to be [approximately]2350 g/d, with the highest amounts ingested during the central and penultimate days of the foraging trip. Foraging success (grams ingested per unit time underwater) was also highest (>370 g/h) at this time. The relationships between foraging strategy, inter- and intraspecific competition, and King Penguin body mass are discussed. Key words: Aptenodytes patagonicus; diving activity; feeding behavior; food mass; foraging range; foraging strategy; global location sensor; King Penguin; multiple-channel recorders; stomach temperature archival units; swim speed., INTRODUCTION King Penguins (Aptenodytes patagonicus) are the second largest of the extant penguin species, having a body mass of [approximately]13 kg (Adams and Klages 1987). Only the congeneric Emperor Penguin [...]