More new submarine cable capacity was deployed last year than the entire undersea bandwidth in service globally in 2011, according to market research firm TeleGeography. That astounding statistic represents international bandwidth growth of 44 per cent in 2014, to reach 211Tb/s. Wholesale carriers and private networks, particularly those of large content providers, continue to invest billions of dollars to upgrade the capacity of existing subsea cables and install new systems.

Far below the surface, fibre-optic cables criss-cross Earth’s ocean floors, blind to the conditions – and the risks – in the cold and dark surrounding them. To channel data across the world reliably, these expensive submarine networks are designed to minimise the number of parts that add to bill-of-material costs and could fail. In this austere culture, until recently, the idea of adding sensors to monitor what’s going on down there would have met with scorn.