In an era where wireless technology and satellite communications are all the buzz, few people realize that the backbone of global communication lies deep beneath the oceans. Submarine communication cables, often overlooked and underappreciated, silently carry 95% of the world’s international data traffic — and they’ve done so for over a century.

The concept of submarine communication cables dates back to the early 19th century. After the introduction of the working telegraph in 1839, the idea of a submarine telegraph line became a topic of interest. Samuel Morse, known for developing Morse code, conducted an early experiment in 1842 by submerging a wire insulated with tarred hemp and India rubber in New York Harbor, successfully telegraphing through it.

It was a game changer. No more letters, no more waiting times, just instant communication over thousands of kilometers — as long as you had the cables for it, that is.

However, the technology for such cables, that could lie at the bottom of the oceanfloor and withstand everything that nature throw’s at it, was not easy to develop. In fact, a key element game from a tree.

The key to a successful long-distance submarine line was finding an effective insulator to prevent electric current from leaking into the water. The breakthrough came with the introduction of gutta-percha, a natural latex obtained from the Palaquium gutta tree, by Scottish surgeon William Montgomerie in 1842. Michael Faraday and Wheatstone soon recognized its potential as an insulator for underwater cables. Thus, the era of submarine communication cables was born.

The first commercial underwater cables

The first commercial attempts to lay submarine cables began in the mid-19th century. In August 1850, John Watkins Brett’s English Channel Submarine Telegraph Company laid the first line across the English Channel. Although this initial attempt, which used an unprotected copper wire coated with gutta-percha, was unsuccessful, it laid the groundwork for future endeavors.

In 1851, the Submarine Telegraph Company successfully laid a protected core cable from Dover to Calais, marking the beginning of a series of successful submarine cable projects. By 1853, cables connected Great Britain with Ireland, Belgium, and the Netherlands, establishing critical telecommunication links.

But compared to the scale of the planet, the distance between the UK and places like Belgium or Ireland is not that great. Making the first transatlantic cables, from Europe to North America, was a much greater challenge.

The Transatlantic Telegraph Cable

One of the most ambitious projects of the 19th century was the laying of a transatlantic telegraph cable.

Cyrus West Field, an American businessman, spearheaded the effort, persuading British industrialists to fund the project. The first attempt in 1858 faced numerous challenges and operated for only a month before failing. The first successful transatlantic cable was laid in 1858. It only lasted for a few weeks, but it was a striking success, providing a vital link between Europe and North America. It showed that it could be done and it showed what needed to be changed as well.

From the 1850s until the early 20th century, British companies dominated the submarine cable industry. Britain’s extensive colonial empire created a high demand for telecommunication links, and British entrepreneurs were willing to invest heavily in building, laying, and maintaining these cables. The strategic geographic locations of British territories also facilitated the shortest and most cost-effective routes for transatlantic cables.

By 1896, British companies owned 24 of the 30 cable-laying ships worldwide. By 1923, British firms still controlled 42.7% of the world’s cables. This dominance was not only due to technological advancements but also because of the British government’s strategic interest in maintaining secure communication lines throughout its empire.

Cables in the Pacific and beyond

The first trans-Pacific cables were completed in the early 20th century. In 1902, the US mainland was connected to Hawaii, and in 1903, Guam was linked to the Philippines. The trans-Pacific segment of the All Red Line connected Canada, Australia, New Zealand, and Fiji by 1902. Japan was integrated into this network in 1906, establishing a comprehensive telecommunication system across the Pacific.

The technology also changed substantially. The first cables were telegraph cables, which need to carry far less information. Telephone cables were different

Early submarine cables were insulated with gutta-percha and protected by layers of iron and later steel wires. The introduction of polyethylene insulation in the 1930s marked a significant technological advancement. Polyethylene’s superior insulating properties eventually replaced gutta-percha and rubber, making cables more reliable and durable.

The 1960s saw the development of transoceanic telephone cables using coaxial cables, transmitting frequency-multiplexed voice signals. High-voltage direct current powered repeaters placed at intervals along the cables, enhancing signal transmission. Although these cables had limited capacity, they marked the beginning of reliable long-distance telephone communication. Not long afterwards, a new technology came in.

The modern fiber optic

These early cables used copper wires in their cores, but modern cables use optical fiber technology to carry digital data, which includes telephone, Internet and private data traffic.

In 1988, TAT-8, the first fiber optic transatlantic cable, was laid, providing 40,000 telephone channels. Fiber optic cables offered significantly higher bandwidth and lower transmission losses compared to coaxial cables. This technological leap facilitated the exponential growth of global internet and data communication.

Modern submarine cables are constructed with multiple layers of protection, including steel wires, polyethylene insulation, and a core of optical fibers. These cables are designed to withstand harsh underwater conditions and have lifespans of over 25 years. They carry an enormous amount of digital data, including internet traffic, telephone calls, and private data transmissions.

However, it’s remarkable just how important these undersea cables are to this day, and how well-developed this underwater cabling system was even more than 100 years ago.

Throughout their history, submarine cables have faced numerous challenges, including attacks by sea life, such as shipworms and sharks, and environmental factors like storms and tidal movements. Advances in cable materials and design have mitigated many of these issues, making modern cables more resilient.

Communication technology continues to advance, but submarine cables remain a vital component of the world’s communication infrastructure, connecting continents and enabling the seamless exchange of information across the globe.