What are underwater and subsea connectors? A complete guide to types, uses and connector design

Underwater connectors, or subsea connectors, are critical to deep-sea operations. They enable power and data transmission between surface systems and submerged equipment. As offshore industries expand, the need for reliable subsea connectivity continues to grow.

Since 2008, DWTEK has supported these missions through integrated underwater solutions, including ROVs, underwater connectors, and offshore services, designed to overcome the limitations of human access at depth.

What are underwater and subsea connectors?

The terms “underwater connector” and “subsea connector” are used interchangeably to describe components engineered to maintain electrical, signal, or data connections in submerged environments. These connectors are widely deployed in subsea pipelines, remotely operated vehicles (ROVs), underwater sensors, and deep-sea communication systems. Unlike standard connectors, subsea variants must endure extreme underwater conditions, including high pressure, saltwater corrosion, and fluctuating temperatures.

Their materials and sealing mechanisms are designed to prevent water ingress, ensuring consistent power transmission, signals, and data even at depth. These specialized connectors are a vital link between underwater infrastructure and surface control platforms in marine systems with critical stability and uptime.

Real-world applications: Where underwater connectors are used

Underwater vehicles and robotics

Robotic platforms such as Remotely Operated Vehicles (ROVs), Autonomous Underwater Vehicles (AUVs), and Unmanned Surface Vessels (USVs) rely heavily on subsea connectors to function reliably in harsh underwater environments. These connectors are used to power motors, thrusters, control units, sonar systems, cameras, and lighting. As vehicle technology evolves, the demand for high-performance data and power transmission continues to grow.

Oil and gas industry

In offshore oil and gas operations, underwater connectors are essential for connecting and maintaining critical subsea infrastructure. They are widely used in subsea distribution units, monitoring systems, data acquisition systems, and pipeline systems, ensuring reliable power and signal transmission across complex and high-risk environments. Stable connector performance is vital for real-time data transmission and remote system control in deepwater conditions.

Offshore wind power systems

In offshore wind energy projects, underwater connectors are commonly deployed in subsea power distribution hubs, where they link control units, transformers, and energy routing systems beneath the surface. These connectors enable modular design and simplify maintenance, allowing for easier integration of new components without taking the entire system offline.

Underwater connectors are also used in floating LiDAR buoys and oceanographic monitoring platforms equipped with sensors like ADCPs (Acoustic Doppler Current Profilers) and optical radars. These systems collect essential data on wind speed, direction, wave height, and ocean current velocity—critical metrics for wind farm planning, site assessment, and ongoing maintenance operations.

Marine research and oceanography

Scientific missions depend on underwater connectors for the reliable operation of equipment such as CTDs (conductivity, temperature, depth sensors), underwater profilers, and time-lapse cameras. These instruments study currents, marine life, and deep-sea ecosystems, often in remote or high-pressure environments.

Defense and naval systems

Underwater connectors are vital components in defense and naval operations, where secure and reliable performance is essential under extreme conditions. These connectors are used in submarine communication systems, diver propulsion vehicles, unmanned underwater surveillance platforms, and sonar arrays. Designed to withstand pressure, corrosion, and electromagnetic interference, they ensure stable power and signal transmission for mission-critical systems operating in harsh marine environments.

Understanding categories of underwater connectors

There are generally three types of underwater connectors: Purely Electrical, Ethernet, and Optical. These can be further classified based on their features, unique shapes, voltage capacities, and application scenarios:

A. Pure electrical connectors provide power transmission to subsea equipment such as motors, lights, or pumps. 

B. Ethernet connectors support power and signal transmission, making them suitable for devices requiring real-time communication alongside electrical supply, such as cameras and sonar systems.

C. Optical connectors, which use fiber optic technology, transmit only signals but are ideal for long-distance data transmission. They offer high bandwidth and excellent noise resistance, especially in applications like subsea telecommunications and extended sensor networks.

Wet-mate vs. dry-mate connectors

Wet-mate connectors are designed to be mated and demated directly underwater, making them highly suitable for subsea systems that require frequent reconnection or maintenance, such as ROV payloads, underwater sensors, and modular devices. These connectors typically feature a rubber exterior and a one-piece molded structure, offering excellent sealing performance under high pressure. However, they require greasing before each use to maintain their sealing function. It’s important to note that wet-mate connectors must be disconnected and reconnected with the power turned off to ensure safety and prevent damage.

In contrast, dry-mate connectors must be connected on the surface before deployment. Once mated, they can function reliably at depth, offering greater rigidity and structural strength. They are typically metal and may feature multiple locking points, making them ideal for fixed installations such as underwater instrument housings, battery pods, and long-term communication modules. Dry-mate connectors are easier to clean and maintain, as they do not require grease and leave no residue. Like wet-mate connectors, dry-mate connectors must be disconnected and reconnected only when power is turned off.

Connector series

Underwater connectors are also grouped into different series, each with unique shapes, voltage capacities, and application scenarios:

• Standard Circular (SC) connectors: With a robust outer shell and larger body, SC connectors can handle up to 600 VDC voltages.
  
  
• Micro Circular (MC) connectors: Highly popular for their compact size and versatility, MC connectors are widely used across various subsea applications. They are ideal for space-constrained devices such as underwater cameras, acoustic sonar, and small sensors. Their voltage capacity typically maxes at 300 VDC.
  
  
• Ethernet Series connectors: Like land-based Ethernet, these connectors transmit high-speed data such as sonar signals, real-time images, and telemetry to the surface in deep-sea conditions.
  
  
• High Power: Designed for demanding electrical loads, supporting up to 1,000 VDC voltages.
  
  
• Penetrator Right Angle: Designed with a 90-degree angled body, this connector prevents cable bending after installation, making it ideal for compact subsea equipment such as underwater sensors, cameras, and instrument housings where space is limited.
  
  
• Metal Shell (Dry Mate): This series is widely used in underwater video systems, diver communications, ROVs, submersibles, towed arrays, and marine biology equipment such as animal tracking devices and current meters. It provides reliable sealing and electrical insulation in fixed or low-maintenance systems.

Connector structures: bulkhead, inline, dummy

The third way underwater connectors are categorized is by mechanical structure and installation interface:

• Bulkhead connectors feature a metal thread installed through subsea enclosures to create a watertight transition between internal and external cables. These are commonly used on ROV housings and sensor modules.
  
  
• Inline connectors are molded directly with cables (typically around 60 cm in length) and used for extensions or branching. They are preassembled, making them easy to use during field operations.
  
  
• Dummy connectors serve as caps or protective covers for unused connector ports. Like anti-dust plugs on laptops, they prevent corrosion, dust, and mechanical wear when connectors are inactive or stored between deployments.

Choosing the right combination of connector series and structure depends on available space, mating frequency, electrical load, and sealing requirements. You can explore DWTEK’s full range of connector series here to find the best fit for your application.

Critical Factors When Choosing Underwater Connectors

Designing underwater connectors involves addressing environmental challenges, mechanical durability, and electrical reliability. The following are essential factors to consider in ensuring long-term connector performance in subsea conditions.

Pressure rating and depth compatibility

Hydrostatic pressure increases significantly with depth, roughly 1 atmosphere for every 10 meters—connectors used beyond their rated depth risk deformation, seal rupture, or catastrophic failure. For example, a connector rated for 1,000 meters may begin to leak or short-circuit at 1,200 meters due to over-compression of sealing components. Deep-sea missions often require pre-deployment validation through pressure chamber testing that simulates absolute operating depths.

Housing and material durability

A connector's outer shell must endure mechanical stress and environmental exposure. Titanium is the material for high-end applications due to its corrosion resistance and strength-to-weight ratio. Stainless steel offers a balance of cost and performance and is widely used in offshore energy. PEEK (poly-ether-ether-ketone) and other engineered plastics are preferred for non-magnetic environments and where weight is a concern, such as near sensitive instruments on research submersibles.

Seal integrity and water ingress protection

A failed seal is one of the most common causes of connector malfunction. Water ingress can cause electrical shorting, corrosion, or even thermal failure under load. To avoid this, manufacturers use multi-layer sealing systems, including overmolding, O-rings, and pressure-compensating gel or oil. In wet-mate connectors, dynamic sealing must be maintained even during the physical act of mating, making precision in seal geometry and material selection crucial.

Electrical performance parameters

Voltage, impedance, and resistance ratings must align with system needs. Signal connectors for sonar or telemetry must ensure low-noise, impedance-matched transmission to avoid data loss. Power connectors must handle high current loads without overheating or developing resistance creep at contact points. Poor electrical performance degrades signal quality and can reduce component lifespan through arcing or micro-corrosion.

How to choose the right subsea connector for your underwater system

Choosing the right underwater connector starts with understanding your system requirements and environmental challenges. Follow this step-by-step guide to identify the best-fit connector for your specific underwater application.

Step 1: Understand your underwater use case and application

What kind of system are you building? An ROV, sonar array, underwater camera, or marine sensor platform? Clarifying your system's function, deployment duration, and constraints helps narrow down connector requirements early.

Step 2: Define performance requirements based on your application

• Connector Type and Contact Option: What kind of connector do you need—wet-mate or dry-mate? How many contact options (or pins) are required? Power-heavy applications like deep-sea power systems may require connectors rated above 10 A, while data systems often need multi-pin layouts optimized for low voltage.
  
  
• Depth and Pressure Rating: How deep will the connector operate? What is the expected hydrostatic pressure? Be sure to cross-check the connector’s rated depth against your mission profile. For example, a 1,500-meter deployment typically requires a connector rated for at least 2,000 meters and validated by pressure chamber testing.
  
  
• Signal vs. Power Transmission: Will the connector carry power, data, or both?
  
  
• Housing Material and Magnetic Sensitivity: Do you have requirements related to corrosion resistance or magnetic interference? Non-magnetic materials like PEEK are often preferred on vessels or near sensitive instruments like magnetometers.
  
  
• Certification and Environmental Standards: Does your project require connectors that comply with environmental certifications such as RoHS and REACH? 

Step 3: Select the underwater connector most appropriate for you

Once your requirements are precise, select a connector series that fits your needs. DWTEK offers various certified connector types and configurations, including micro circular, standard circular, low profile, rubber molded, Ethernet, penetrator (right-angle and straight), and wet and dry metal shell types. Explore DWTEK’s full connector range for more details.

Not sure which underwater connector fits your system? DWTEK also provides custom connector design tailored to your needs. Please reach out to learn more!

Why choose DWTEK as your trusted underwater connector manufacturer

DWTEK stands out with its strong engineering expertise and a proven track record in underwater connector development.

Made-in Taiwan Proven Quality for Harsh Marine Conditions

DWTEK's underwater connectors are engineered to perform reliably in the most demanding subsea environments. Each product undergoes rigorous in-house testing, including pressure chamber simulations up to 600 bar (equivalent to 6,000 meters depth) and temperature cycles ranging from -40°C to 60°C, ensuring exceptional sealing integrity and corrosion resistance. These connectors are not only tested in controlled environments but are also deployed in our own ROVs and ROV TMS system (Tether Management System) during offshore wind farm operation and management, and deep-sea inspection missions, providing continuous field validation.

In-House Engineering and Customization Expertise

With over 15 years of experience, DWTEK offers end-to-end customization capabilities, from design and machining to molding and assembly. Our in-house engineering team specializes in developing tailored connector solutions for a variety of applications, including:

• Remotely Operated Vehicles (ROVs)
  
  
• Underwater sonar systems
  
  
• Integrated underwater sensor networks
  
  
• Specialty marine systems

We also support custom designs for double-ended and multi-ended connectors, enabling more efficient integration in complex subsea system layouts.

Responsive Support and Commitment to Durability

Our dedicated team provides responsive technical support and comprehensive design documentation, ensuring long-term reliability and flexibility across every underwater mission. DWTEK's connectors are designed to withstand the rigors of high-risk marine operations, and our hands-on approach ensures that our products meet the highest standards of durability and reliability.

FAQs

Q1. What’s the difference between subsea and underwater connectors?

“Underwater connector” and “subsea connector” are often used interchangeably. 

Q2. How deep can underwater connectors operate?

Depth capability depends on the connector’s pressure rating and sealing design. Commercial-grade connectors often operate at depths up to 1,000 meters, while specialized deep-sea connectors can exceed 6,000 meters. DWTEK offers pressure-tested solutions rated for a wide range of subsea depths.

Q3. What types of signals can be transmitted?

Underwater connectors transmit power, analog signals, digital data, Ethernet communication, and fiber optic signals. The specific signal type determines contact layout, shielding requirements, and impedance design.

Q4. What are Male and Female Connectors?

We typically find plug and receptacle connectors in a connector series. The plug—commonly referred to as the male connector—features one or more exposed pins or contacts. The receptacle—known as the female connector—contains matching sockets that receive the pins. This male-female pairing ensures proper alignment, secure mating, and signal continuity during operation.

Q5. How are connectors tested for marine durability?

Marine-grade connectors undergo pressure chamber testing, salt spray corrosion tests, and thermal cycling to simulate long-term exposure. Seal integrity, electrical performance, and structural resilience are evaluated to ensure the connector performs reliably in challenging subsea environments over time.

Q6. What are the differences between DWTEK underwater connectors and competitors’ products?

While there are several long-established players in the subsea connector market, DWTEK distinguishes itself through its integrated in-house development, pressure-tested field validation, and a broad catalog of connector shapes and configurations. DWTEK specialize in successfully deployed in deep-sea applications across various industries, ensuring performance that meets real-world demands.

Conclusion

Choosing the right underwater connector is critical to the success of any subsea system. From ensuring reliable power and data transmission to protecting equipment from water ingress and pressure failure, the connector directly affects underwater operations' safety, performance, and longevity.

With years of experience in harsh marine environments and a commitment to engineering precision, DWTEK offers proven subsea connectivity solutions trusted by industries worldwide. Our field-tested products and custom engineering capabilities make us a dependable partner for complex underwater missions. Explore DWTEK’s full range of subsea connectors or contact us to discuss your specific underwater connectivity needs.