Tethys Robotics Raises €3.5 Million Pre-Seed Round to Scale Autonomous Underwater Inspection Technology

Swiss underwater robotics startup Tethys Robotics has secured €3.5 million in pre-seed funding to accelerate the development and commercialization of its autonomous subsea inspection technology. The Zurich-based company, which originated as a spin-off from ETH Zurich, aims to transform hazardous underwater operations by replacing manual diving work with advanced robotic systems.

The pre-seed round was led by Redstone and backed by a group of European investors that includes Euregio+, Alpine VC, Zürcher Kantonalbank, the ETH Foundation, Kickfund and Venture Kick. The mix of venture capital, institutional investors and innovation-focused organizations reflects growing confidence in deep-tech solutions emerging from academic research environments.

Founded by a team of engineers and researchers, Tethys Robotics focuses on automating safety-critical underwater tasks using its flagship system, Tethys ONE. The compact autonomous underwater vehicle is designed to operate in demanding subsea environments and can be deployed either remotely or in fully autonomous mode. According to the company, the system is capable of operating at depths of up to 300 meters and is engineered to perform reliably in strong currents and low-visibility conditions.

Tethys ONE is intended for use in sectors where underwater work is both dangerous and expensive. Key applications include offshore wind farm inspection, energy infrastructure monitoring, subsea cable surveys, unexploded ordnance identification, and search-and-rescue missions. By combining advanced sensor technology, navigation software and real-time data visualization, the system is positioned as an alternative to traditional inspection methods that rely heavily on human divers or large, crewed vessels.

The newly raised capital will be used to expand Tethys Robotics’ engineering and data science teams, scale production of its robotic platforms and move from pilot projects to broader commercial deployment. The company has already completed more than 30 pilot projects with customers across energy and offshore sectors, providing early validation of its technology and helping refine its product for industrial use.

Tethys Robotics’ leadership has stated that reducing risk to human workers is a central motivation behind the company’s mission. Underwater inspection and intervention tasks are among the most hazardous in industrial operations, particularly in offshore environments. By enabling autonomous data collection and inspection, the company aims to improve safety while also reducing operational costs and downtime for asset operators.

The participation of Redstone as lead investor highlights investor interest in robotics companies that address real-world industrial challenges. Redstone is known for supporting technology startups at early stages, particularly those emerging from European research institutions. Other investors in the round provide complementary support, ranging from financial backing to access to innovation networks and industry expertise.

Beyond funding, Tethys Robotics is also building strategic partnerships to support market entry. The company has entered into a cooperation agreement with SeaRenergy Offshore Holding GmbH, integrating its autonomous underwater systems into broader offshore service offerings. This partnership is intended to accelerate adoption of Tethys ONE in commercial offshore operations, particularly in the renewable energy sector.

With the global offshore wind and subsea infrastructure markets continuing to expand, demand for efficient and safe underwater inspection solutions is expected to grow. Tethys Robotics is positioning itself to benefit from this trend by offering a lightweight, modular system that can be rapidly deployed without the need for extensive surface support.

The €3.5 million pre-seed investment marks an important step in Tethys Robotics’ transition from research spin-off to commercial company. With fresh capital in place, a growing customer pipeline and strong investor backing, the company is preparing to scale its operations and establish itself as a key player in the autonomous underwater robotics market.