ABSTRACT: We investigated the foraging behaviour of king penguins in relation to sea-surface temperature distribution over 3 years near the Crozet Archipelago, South Indian Ocean. Within their range there are 2 hydrographic frontal systems, whose seasonal patternsof productivity are predictable. These are the Polar Front and the Sub-Antarctic Front. During the austral summer the foraging range of breeding king penguins was restricted to the Polar Frontal Zone, limited to the south by the Polar Front and to thenorth by the Sub-Antarctic Front. Most birds travelled towards the colder water situated south of Crozet, while other birds moved east to warmer water. Birds travelling south spent more time than expected in the coldest waters generally associated withthe Polar Front. Birds travelling east reached the southern limit of the Sub-Antarctic Front (sea-surface temperature between 8 and 10°C). Within the Polar Frontal Zone birds differed in their foraging behaviour, with incubating birds remaining at sea forlonger times and covering longer distances. During the incubation period, king penguins travelling south tended to spend their time in areas with a sea-surface temperature between 4 and 5°C, which coincide with the location of the Polar Front. Thoughthese birds remained at sea longer, they did not go any further south than birds having an egg ready to hatch or than birds in the brooding period, which appeared to travel more directly towards the Polar Front. As the breeding season progressed, thePolar Front moved further south, out of the range of the king penguins especially those with a newly hatched chick that were limited in the amount of time that they could spend at sea. King penguins breeding at Crozet may choose between 2 strategies, inwhich some birds forage towards the Sub-Antarctic Front but most travel south towards the Polar Front.