What is the fastest bird when diving?

The peregrine falcon, also referred to simply as the peregrine, is a bird of prey (raptor) in the family Falconidae known for its speed. A large, crow-sized falcon, it has a blue-grey back, barred white underparts and a black head. As is typical for bird-eating (avivore) raptors, peregrine falcons are sexually dimorphic, with females being considerably larger than males. Historically, the bird has also been known as the "black-cheeked falcon" in Australia and the "duck hawk" in North America.