What is Subsea Cable?

Meet the Cable: Subsea Cables 

Subsea cables (also called submarine cables) are specialized, highly ruggedized fiber optic cables that cross the seabed between land-based stations to carry telecommunications signals. They are the backbone of global internet and data communications and transmit data such as internet traffic, telephone calls, and private data. Subsea optical cables carry over 95% of international data. Google, Meta, Microsoft, and Amazon are major investors in new cable. Subsea power cable is used to transmit electricity between countries or to offshore platforms.

According to Telegeography, as of early 2025, there are more than 600 active and planned subsea cables stretching more than 1.48 million kilometers across the ocean floor. The number of cables is constantly changing as the old or damaged ones are decommissioned. Typically, newer cables are capable of carrying more data than cables laid 15 years ago; the new MAREA cable, a transatlantic cable built by Microsoft and Meta, connecting the U.S. and Spain, is capable of carrying 224 Tb/s. Subsea cable is deployed using specialized ships. Nearer to the shore, the cables are buried under the seabed to protect them from damage caused by fishing boats dragging anchors or human tampering, but in the deep sea they are laid directly on the ocean floor. There is a perception that sharks bite and damage subsea cables, but this is vastly overstated. According to the International Cable Protection Committee, early iterations of cable showed evidence of damage from marine life, but those events led to design improvements of the cables’ protective sheathing that effectively eliminated the problem. Accidents like fishing vessels and ships dragging anchors account for two-thirds of all cable faults. Environmental factors like earthquakes also contribute to damage. Less commonly, underwater components can fail. In recent years, deliberate sabotage has also been an issue between warring nations.

Design Notes 

Very specialized ruggedization features enable subsea cable to perform in underwater environments. Waterproof and pressure resistant materials, steel wire armoring, and plastic sheathing provide durability and protection to the optical fibers.

Winchester Interconnect’s subsea cables, particularly its Xtreme Cable SubSea Instrumentation Cables, are engineered for demanding underwater environments such as offshore energy, defense, and oceanographic research. These cables are designed to ensure reliable performance under high pressure, temperature extremes, and mechanical stress, utilizing aluminum/mylar shielding with a drain wire and shield isolation to minimize electromagnetic interference. Features an overall synthetic fiber strength layer, providing an 800 lb break strength, and is encased in a flexible black polyurethane jacket for abrasion resistance.

Environmental Ratings:

• Temperature Range: -25 °C to +90 °C
• Power Rating: 600V
• Depth Rating: Data pairs rated for depths up to 2 km

Connectorization

iCONN Systems’ wet mate OctoCONN connector solutions connect deep sea cables and other underwater applications.

Patrick McLoone, iCONN Systems, said the company’s wet-mate connectors are suitable for use in air, saltwater, and freshwater, and are most popular for cable-to-cable connections. “We currently have about 15 different OctiCONN Connector Sets in operation [as of early 2025]. As of now we will rate our OctiCONN’s to five years, as that is how long we have been able to test the original designs that still hold. But the true lifespan is very application-specific. Freshwater vs Saltwater, Constant Mating, and Demating versus a one-time mate, depth rating (ties into organic material growth), all are factors in deep sea applications.

Wet-mate connectors Sensors and monitors for ocean/water movement, fish farms and other agriculture, unmanned vehicles (ROV’s & AUVs), Oil & Gas, Military. Can be used to connect/disconnect optical cables underwater.

Fusion splicing is used in place of connectors for some applications. This involves permanently welding the glass fibers together.

Trexon offers a comprehensive suite of subsea cable solutions tailored for mission-critical applications across industries such as offshore energy, defense, marine, and renewable sectors. These products are engineered to perform reliably in harsh underwater environments, addressing challenges like high pressure, extreme temperatures, and mechanical stress.

Markets and Applications

Datacom and Telecom, Military and Aerospace (naval applications)

Suppliers

iConn Systems (deep sea cable connectors), Trexon, Winchester Interconnect

Like this article? Check out our other Meet the Connector and Connector Basics articles, our Transportation Market Page, and our 2024 and 2025 Article Archives. 

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