A medium-sized, bulky dark petrel with a large head and long pointed wings. It often shows a grizzled, gray scaly muzzle around the bill. It flies fast with a flexed wrist and its heavy head angled downward, giving it a characteristic appearance. It breeds on subantarctic islands between the Tristan group and western Australia, dispersing across the southern oceans between 30 and 50°S, where it is a deep ocean specialist. Several species are similar to Great-winged Petrel. Gray-faced Petrel, sometimes considered the same species, breeds off New Zealand and is almost identical except for a more extensive grizzled face patch. The smaller Kerguelen Petrel has a more contrasting silvery underwing. The gadfly petrels mostly have more pale patterning on the underwing or belly and lack the bulkiness of Great-winged Petrel.