Underwater Robots · Part of The Humanoid Group

Bio-Inspired Swimmers

Not every underwater robot uses propellers. Researchers have long studied how fish, rays, eels and octopuses move, building robots that swim with fins, flexible bodies or soft arms. Most remain research platforms, but the ideas are spreading.

By Kenji Nakamura · Updated October 2026

Why copy nature

Fish and other swimmers move efficiently, turn sharply and hold position in turbulent water, all things that are hard to achieve with conventional thrusters. Fin- and body-driven robots aim to borrow some of these traits. Potential benefits include quieter movement, less disturbance to sediment and wildlife, and better manoeuvring close to delicate structures such as reefs. The challenges are real too: flexible mechanisms are harder to build, seal and control, and many designs are slower or carry smaller payloads than propeller-driven vehicles.

Forms you will see

Bio-inspired designs vary widely. Fish-like robots flex their bodies or tails to swim. Ray-inspired designs flap broad fins and can glide. Eel- and snake-like robots are explored for moving through narrow spaces and around pipework. Soft robots inspired by octopuses use flexible arms to grasp fragile specimens without crushing them. Some are built mainly to study how animals swim, others to test new materials or control methods, and a few are developed with inspection, monitoring or education in mind.

Where they fit today

For buyers, bio-inspired swimmers are mostly something to watch rather than to deploy at scale. Many are research prototypes or education kits, and their capabilities differ widely from one design to the next. If you are evaluating one, ask what it has been tested on, how long it runs on a charge, how it is controlled and recovered, and whether spare parts and software updates are available. For routine inspection work today, a conventional ROV is usually the more practical choice.

Sources and further reading

Self-powered soft robot in the Mariana Trench — Nature (Li et al.).
Snailfish-inspired soft robot with electronics set in silicone, tested in the Mariana Trench.
Exploration of underwater life with an acoustically controlled soft robotic fish — Science Robotics (Katzschmann et al.), via MIT DSpace.
The SoFi study: a soft robotic fish steered acoustically by divers to film reef life at close range.
Ray-inspired robots: recent advances in actuation and control — npj Robotics (Freyhof et al.).
Review of robots modelled on rays, comparing actuators, control methods and the performance gaps still open.

Common questions

Can I buy a robotic fish for inspection work?

Few are built for routine commercial inspection yet. Most are research or teaching platforms, so a conventional underwater drone remains the safer choice for regular checks.

Are bio-inspired robots better for marine life?

They may disturb wildlife less, because they can move more quietly and stir up less sediment. The evidence is still emerging, so treat claims for any single design with care.

ROVs vs AUVs — Tethered and piloted, or untethered and autonomous: how the two main vehicle types differ.
Inspection & Maintenance — Hulls, pipelines, harbour walls and fish farms: where underwater robots take on routine checks.
Research & Exploration — Mapping the seabed, sampling the ocean and reaching depths people cannot.
Bio-Inspired Swimmers — Robots that swim like fish, rays and eels, and what they could mean for underwater work.
ROV Pilot Training — How ROV pilots are trained and assessed, from offshore competence grades to small inshore teams.
Drones for Fish Farms — Net checks, mooring inspections and fish behaviour: how underwater drones fit into work on a fish farm.
Hull Cleaning and Biofouling — In-water hull cleaning robots, the biofouling rules behind them and what ports expect before cleaning starts.
Hobby Underwater Drones — Depth, tether, camera and handling: what to compare before buying an underwater drone for fun or filming.
Cable and Pipeline Inspection — How ROVs and AUVs follow and inspect subsea cables and pipelines, and what operators must record.
Latest updates — Offshore wind owners are buying more inspection work, research fleets are planning subsea docking, and hull robots are earning class approval. These figures and dated updates show where underwater robotics stands now.
About us — What we cover, how we source every figure, and who publishes this site.

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