Philip Hoare, author of the 2009 Samuel Johnson Prize winning Leviathan or, The Whale, shares photographs from his whalewatching expeditions off Cape Codd and the Azores
The waters of the Azores are rich in marine mammals, especially dolphin. Bottle nose, spotted, striped and Risso's dolphin are regularly seen, as are common dolphin, here riding the bow of our boatPhotograph: Philip HoareHere two humpbacks are drag-feeding at the surface. You can even see the sand-eels jumping out, as if to escapePhotograph: Philip HoareFin whales are second only to blue whales in size, reaching 85 feet in length. Known as 'greyhounds of the sea', individuals may be identified from shadings known as chevrons on their backs.Photograph: Philip HoareStellwagen Bank, off Cape Cod, is a fertile feeding ground for humpbacks when they return from their six-month fasts in the CaribbeanPhotograph: Philip HoareOften, humpbacks will breach repeatedly, in the same spot, for up to half an hour. The energy used in these displays is immense; breaching seems to occur after the animals have been feedingPhotograph: Philip HoareA sure sign of feeding humpbacks is a cloud of opportunistic gulls. Sometimes birds will enter the whales' mouths to pluck out sand-eels and occasionally get trapped, only to be released at the next gulpPhotograph: Philip HoareThe underside of every humpback's tail, or flukes, carries a unique pattern which allows individuals to be identified. This whale is named Filament, after the narrow black line on its righthand flukePhotograph: Philip HoareThis humpback appeared off the side of the boat last month. It hung perpendicularly, watching us through the water, like a watery alien. The onboard naturalist admitted he'd never seen this strange position beforePhotograph: Philip HoareNorth Atlantic right whales are one of the rarest species - fewer than 400 remain. The strange growths on their heads are known as callosities, and are filled with parasites known as whale lice, or cyamidsPhotograph: Philip HoareA diving sperm whale off Pico, in the Azores. The deep waters here are perfect feeding grounds for these whales, 90% of whose diet consists of squid Photograph: Philip HoareSperm whales may hang at right angles to the surface, looking up through the water to see what's happening, in behaviour known as 'spy-hopping'Photograph: Philip HoareNo-one knows why whales breach - it may be a means of communication, or ridding their bodies of parasites. To me, it just looks like fun.Photograph: Philip Hoare