The iceberg is very large, so even if it doesn't envelop the island it could create a detour of up to 140km between a penguin and its feeding waters, a 280km ad

The iceberg is very large, so even if it doesn't envelop the island it could create a detour of up to 140km between a penguin and its feeding waters, a 280km addition to every trip - and that's only if it has access to satellite images to plan its route. On the surface, that penguin would only see a huge wall of ice with no indication which way would be shorter.