Only 1% of the world’s data moves via satellite, the rest is carried through cables. Deep-sea cables must be extremely strong to survive cuts, nicks and bites from marine vessels and creatures, besides cyclones. They should withstand extreme pressures at places where they lie miles under the surface of water. To achieve that strength, a deep-sea cable is largely made up of steel wires that play no role in data transmission. The real job is done by a very thin core of fibre.