Just to add, the undersea cables are of armoured type. Here's some pics of 19th century cable : This very early telegraph cable connected Havana, Cuba and the United States in the late 19th Century. http://w1tp.com/mcable97.htm Shark bite force ( off the net ) : Worst is Great White Shark = 1.8 tonnes of biting force ( University of New South Wales made 3D models of the skull of an 8ft male great white using images from a CT scanner?? ) Normal locations of Great Whites = Worldwide in coastal marine waters, and also around oceanic tropical islands, but more common in cold and warm temperate regions, and apparently rare or absent from most of the western Indian Ocean, Indonesia, and tropical Central America. Most common off California, Australia, and South Africa. The white shark is primarily a continental shelf inhabitant, cruising through relatively shallow waters either near the surface or close to the bottom. It also is found off oceanic islands and inshore bays and has even been captured on a bottom as far down as 4,199 ft (1,280 m). BEHAVIOR Whites are solitary and nomadic, and may occur in pairs, but feeding aggregations of some ten individuals also have been observed. It is known that they will leap completely out of the water (breaching) when capturing surface prey (or perhaps for other reasons). They are even capable of breaching vertically in a manner similar to dolphins. "Spy hopping" (when the shark will maintain its head out of the water as if to search the surroundings) and "repeated aerial gaping" (RAG; when the shark "bites" the air with its head clear out of the water) also have been observed. The white shark is known to satisfy its curiosity by circling intended prey items, or even boats and divers. It is capable of great bursts of speed. While feeding, their eyes roll back in their sockets. There may be segregation of individuals according to size. FEEDING ECOLOGY AND DIET The white shark is a formidable predator, feeding mainly on numerous families of bony fishes (as well as a large variety of sharks, even the basking shark), sea turtles, marine mammals (pinnipeds and whale carcasses), and even sea birds resting on the surface. Invertebrates also may be eaten (such as crabs), but most of its food comes from fishes and marine mammals taken from the surface or in the water column. White sharks are one of the top predators in the ocean; however, they sometimes fall prey to orcas (killer whales).