Underwater Robotics: How It Works and Examples

These bots help us uncover mysteries of the deep.

Written by Brooke Becher
Published on Jan. 23, 2024
Underwater Robotics: How It Works and Examples
Image: Shutterstock

We have complete maps of the moon and Mars. Meanwhile, the ocean on our own planet remains 80 percent unexplored. This is where mechanical devices known as underwater robots come in.

What Is Underwater Robotics?

Underwater robots are mechanical devices designed to operate in subaquatic conditions without direct human intervention. They are typically used for ocean exploration, underwater infrastructure maintenance, environmental monitoring and underwater photography.

Underwater robots generally fall into one of two categories — remotely operated vehicles (ROVs) and autonomous underwater vehicles (AUVs). The former refers to unmanned drones remotely controlled by an operator, while the latter are pre-programmed to respond to their environments without human intervention.

Typically, underwater robots are equipped with sensors, cameras and arm-like manipulators to perform tasks while submerged. Collectively, these mechanical devices gather more information about the ocean.

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What Are Underwater Robots Used For?

Originally, underwater robots were used for defense purposes — either as remotely controlled missiles or recovery vehicles tasked with collecting sunken artillery. These sub-aquatic machines have since been developed to study marine wildlife and habitats, monitor environmental conditions, maintain underwater structures (such as pipelines and offshore platforms), manage fisheries and even carry out search and rescue missions.

Deep-sea exploration isn’t without its challenges though. Starting at the aphotic zone located 200 meters below, robots must be able to withstand extreme conditions like high pressure, low temperatures, minimal visibility, upkeep issues like corrosion and delayed communications.

Even so, the collective interest to explore the ocean is rising. An already underway global initiative, known as Seabed 2030, is trying to produce a complete map of the ocean floor by the end of the decade.

And with recent advances in subsea tech — including the following list of deep-diving and seafaring robots — it’s never been more possible.


Examples of Underwater Robots

OceanOneK is a diving humanoid robot with a maximum depth of 1,000 meters. | Video: Stanford


OceanOneK is a five-foot, deep-sea diving humanoid built for exploration. Developed by the robotics lab at Stanford University, the robot is equipped with advanced haptic feedback systems and stereoscopic vision that allow human operators to “feel” like they’re swimming the depths, interacting with the environment and manipulating submerged objects via eight multi-directional thrusters. With a maximum depth of 1,000 meters, OceanOneK was initially designed to study out-of-reach coral reefs and recover archaeological artifacts, and has since been used to explore shipwrecks, sunken planes and submarines.


BIOSwimmer is a large, robotic tuna fish used for harbor security and ship inspection. | Video: BostonEngineering


Resembling a tuna fish, BIOSwimmer is an unmanned, biomimetic underwater robot designed to enhance port security and monitor submerged infrastructure. Thanks to its biologically inspired framework and modular design, the five-foot, 110-pound drone, developed by Boston Engineering, is highly maneuverable in constricted spaces or turbulent waters and can be customized for a variety of applications. This includes tactical missions, area searches and harbor surveillance.


The Wave Glider is a self-contained data collection system skimming the seas. | Video: Liquid Robotics

The Wave Glider

The Wave Glider is an unmanned, autonomous surface vehicle designed for ocean monitoring and data collection. Made byLiquid Robotics, it’s essentially a surfboard-sized float tethered to a subsurface wing rack, which hangs about eight meters deep, that uses wave energy for propulsion. Each vehicle includes a self-contained data collection system, complete with an on-board computer, configurable sensor modules, real-time communication as well as solar panels and battery packs to keep it all running. Because of its built-in self sufficiency, these vehicles can operate for up to 12 months of emissionless travel without fuel, external power sources or a crew. So far, Wave Gliders have covered about 2.3 million miles of ocean. Their primary use cases are for environmental monitoring, defense and maritime surveillance, marine research and data collection.

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Belle is a soft-robot spy, used as an informant for marine research. | Video: CBS News


Belle is a soft robotic fish designed by mechanical engineering students at ETH Zurich that collects environmental DNA samples. The three-foot-long, autonomous drone replicates the biomimicry of an actual fish, with a self-propelling silicon tail fin. It uses artificial intelligence to navigate its location while taking isolated samples and recording high-resolution video. Like a spy, Belle’s incognito appearance allows the robot to explore delicate ecosystems and marine life up close with minimal disruption. Developers created Belle to assist marine biologists with their studies on the health and biodiversity of reef ecosystems impacted by overfishing, pollution and climate change.


The AlgaRay is a robotic mantaray that sinks sargassum and reduces carbon dioxide emissions. | Video: Waterlust


Made in the likeness of a manta ray, the AlgaRay is a solar-powered robot designed to reduce carbon emissions by allowing seaweed to sink down to the seafloor and decay. To do this, the 32-feet-long yellow drone scoops up batches of brown algae and dives 135 meters below the surface, crushing their air sacs and thereby eliminating their buoyancy. The company estimates that one AlgaRay can sink up to eight tons of carbon dioxide in the span of three months. 


The Aquanaut | Video: IEEE Spectrum


The Aquanaut is a hybrid underwater robot with two modes. As an AUV, the orange, blimp-shaped submarine autonomously scans seabeds up to 200 kilometers in one trip. Like a Hasbro transformer, the vehicle can transition into a humanoid ROV, where it extends two robotic arms from its front end that enable precise object manipulation. In this mode, Aquanaut can perform many maintenance-related jobs on subsea work sites — like turning valves or using tools — often tasked to human divers. Equipped with sensors and grippers, the all-electric, tetherless Nauticus Robotics’ flagship model is designed for subsea inspection, maintenance and intervention tasks in the oil and gas industry.

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Eelume is a self-propelling robotic arm designed to maintain underwater infrastructure. | Video: Kongsberg Gruppen


Eelume is a snake-like robot specifically built to service subsea infrastructure. This autonomous machine is essentially a self-propelled robotic arm able to navigate through confined spaces and reach previously inaccessible underwater locations. It is a modular machine, with customizable thrusters, joints, sensor modules and different payload capacities adjusted to its application. Depending on the project, Eelume equips interchangeable tooling — from inspection and brush kits to grabber and cutter heads — to carry out jobs. Many of these robots are housed at docking stations and designed to live permanently underwater. 


Equinor’s subsea drones would deliver carbon dioxide to ocean floor reservoirs. | Video: Equinor

Subsea Shuttle

Still in the conceptual stage, Equinor’s Subsea Shuttles are 400-feet-long, autonomous submarines that would be used to transport carbon dioxide to deepwater storage facilities. This process, known as carbon sequestration, removes carbon dioxide from the atmosphere. Using a flowline, these battery-powered, submersible drones would also be able to transport and offload other materials, such as oil, water or gas, for other applications.


Frequently Asked Questions

According to ZipRecruiter, the average annual salary of an underwater robotics engineer is about $105,605 per year.

The most celebrated underwater robots are Argo, ANGUS and Jason Junior, which together discovered the remains of the Titanic in 1985.

Given their environment, underwater robots are prone to short circuiting caused by water damage. Most are battery operated, which shortens their duration of operation, and suffer from low bandwidth for communication since water absorbs and scatters transmission signals. 

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