Most people are not aware that undersea cables carry over 99% of
the internet and other electronic traffic between continents,
with the small remainder provided by satellites.
The first
transcontinental undersea cable was completed in 1858 to deliver
telegraph messages between the US and England. As of 2019, there
are over 400 active undersea fiber cables in place that stretch
over 745,000 miles (1,198,961km). Cables are laid down using
specially-modified ships that carry the submarine cable on board
and slowly lay it out on the seabed. Undersea cables are
designed for a 25-year life, and so cables are regularly being
retired and replaced.
These cables are owned
by countries, cable operators, and companies, such as Google,
Facebook, etc. Huawei Marine Networks Co., majority owned by the
Chinese telecom giant, recently completed a 3,750-mile cable
between Brazil and Cameroon. It also recently started work on a
7,500-mile cable connecting Europe, Asia, and Africa in addition
to finishing up links across the Gulf of California in Mexico.
There is an average of
about 25 undersea fiber cuts per year, caused by earthquakes,
underwater mudslides, ship anchors, and even a few from sharks.
Repairs are made by ships that pull the cut ends of the fiber to
the surface and splice them back together.
Incidentally,
as an indicator of speed, 4.8 million HD movies could stream
at the same time in high-definition through one strand, in one
direction, of the 4,104 mile (6,600km) Marea cable from Spain
to the United States. The cable is composed of an eight-pairs
fiber-optic thread bundle, a bit larger than the size of a
garden hose.