How to lay intercontinental optical cables

Laying intercontinental optical cables involves meticulous planning, specialized cable design, deployment via cable-laying ships, and ongoing maintenance to ensure global connectivity.

Planning and Route Mapping

The first step is careful route planning across the ocean floor. Experts use sonar and other surveying technologies to map underwater terrain, avoiding hazards such as trenches, mountain ranges, shipwrecks, and sensitive ecosystems. Geopolitical factors, including territorial waters and fishing zones, are also considered to minimize legal and operational risks. Detailed seabed surveys assess depth, terrain, and environmental conditions to determine the safest and most efficient path for the cable ( ).

Cable Design and Manufacturing

Submarine fiber optic cables are specially engineered to withstand harsh underwater conditions. They consist of ultra-thin glass fibers for data transmission, surrounded by multiple protective layers including steel armor, waterproof jackets, and polymer coatings. These layers protect the cable from water pressure, currents, marine activity, and potential physical damage. Modern cables are typically about 25 mm in diameter and weigh around 1.4 tonnes per kilometer in deep-sea sections ( ).

Deployment Process

Deployment requires specialized cable-laying ships equipped with plows or remotely operated vehicles (ROVs). The cable is gradually lowered to the seabed, with shallow sections often buried up to 1000 meters to protect against anchors and fishing gear, while deeper sections rest on the ocean floor. At landing points, the submarine cable is spliced to terrestrial networks using watertight splice boxes to prevent corrosion and signal loss ( ).

Signal Transmission and Maintenance

Data travels through the cable as pulses of light, with technologies like Dense Wavelength Division Multiplexing (DWDM) allowing multiple data streams simultaneously. To maintain signal strength over vast distances, repeaters are installed approximately every 60–70 kilometers. Continuous monitoring using sensors helps detect damage from natural events such as earthquakes, and maintenance teams can repair or replace damaged sections as needed ( ).

Testing and Quality Assurance

After installation, the entire cable system undergoes rigorous testing for signal continuity, loss, and integrity. This ensures reliable high-speed communication across continents and long-term durability of the network ( ). By following these steps—planning, designing, deploying, splicing, testing, and monitoring—intercontinental optical cables provide the backbone for global internet and telecommunications infrastructure, enabling seamless data transfer across continents ( ).