The top four underwater and extreme‑environment data centres

It’s hard to imagine that data centres may find their homes on the ocean floor, but startup founders believe this may be the answer.

It’s no secret that AI data centres generate vast amounts of heat, so increasingly advanced cooling systems have been developed to handle it and prevent hardware from slowing down, failing or melting.

Now traditional cooling methods are falling short, as air cooling, fans and chillers have become inefficient at removing the extreme heat produced by modern AI workloads.

To combat this, startups have begun looking to other areas in our planet to cool these data centres down, particularly the ocean.

Research into ocean usage in data cooling began over a decade ago. In 2015, Microsoft launched a research initiative, dubbed Project Natick, that tested whether self‑sustaining sealed data centres could survive on the ocean floor. The results found that submerged servers proved to be twice as reliable as land‑based equivalents, with far fewer failures due to the nitrogen‑filled atmosphere and lack of human interaction.

The ocean is able to provide near‑limitless cooling capacity, minimises land constraints and is also a direct form of access to renewable power.

So, in honour of National Data Centre Day, here is a list of the top four underwater and extreme‑environment data centres that have the potential to reshape where our data homes are situated.

Panthalassa

Panthalassa is a US‑based startup that is building autonomous, wave‑powered offshore data‑centre nodes designed to run AI inference at sea. The node is not anchored, using a hull‑shaped propulsion system to steer itself without engines or fuel, meaning it lives out in deep water where the waves are strong.

The technology works by using a wave‑to‑power system. A spherical buoyancy top keeps the node afloat and a long tube extends deep underwater. As waves move the structure up and down, water is forced into the tube, which turns the turbines inside to convert the motion into electricity.

AI chips are inside the watertight compartments that hang below the floating node, sealed and kept dry. This allows the ocean to act as a free, passive cooling system, which extends chip life.

The results are then sent back to land via Starlink. The company focuses on longer AI inference jobs rather than chatbots or searches.

The startup was founded by Garth Sheldon‑Coulson, CEO, and Brian Moffat, Chief Innovation Officer, back in 2016. Since its launch, Panthalassa has raised a total of $193 million, with its most recent funding round recorded in May 2026, where the company raised $120 million in a Series B round.

Investors include Peter Thiel, Super Micro Computer, Lowercarbon Capital and Marc Benioff’s TIME Ventures. The financing helped fund their pilot manufacturing facility in Portland and the deployment of Ocean‑3 nodes in 2026.

Subsea Cloud

Subsea Cloud is a modular underwater data‑centre capsule developer that is designed to cut power usage by 30–40%. The US‑based startup seeks to eliminate freshwater consumption entirely by using seawater as the cooling system.

The company has developed sealed data‑centre capsules that sit underwater. The capsules contain high‑density GPU racks, including reservations for 2,048 Nvidia H100 GPUs, cooled directly by surrounding seawater.

Their capsules look like giant metal submarine‑like boxes that are sealed and dry inside. The capsule connects back to the grid, with power and data travelling through cables to shore.

The capsules can be deployed in different locations, scaled or replaced easily. The pods can be deployed quickly and cheaply compared to other underwater data‑centre startups.

Sam Mendel, CEO, and Eric Kim, CTO, founded the company with an aim to focus on cost reduction in data centres. Both have backgrounds in robotics, underwater systems and renewable energy.

Subsea Cloud is still an early‑stage startup compared to its competitors but did raise $500k in a seed round backed by Y Combinator in 2024.

Aikido

Aikido is a Japan‑based offshore infrastructure startup developing floating wind platforms containing full AI data centres.

The company bolts the data centres directly onto floating wind turbines. This creates a single steel unit that generates its own renewable power and cools using seawater.

The bottom half of the wind turbine is where the data centre is located, including racks of GPUs, servers and cooling systems sealed inside a steel structure. This is called the AO60DC platform.

The platform is mostly self‑powered. The wind turbine produces 15–18MW of renewable power and the data centre inside uses 10–12MW of that for AI compute.

There is a large battery system onboard that stores excess wind power, allowing operations to continue running even when wind drops. The steel hull sits in cold water, which helps cool servers.

The platforms are deployed 200 miles from major cities, keeping latency under 10ms and allowing many AI workloads to run fast enough.

Aikido is led by CEO Sam Kanner, who positions the company as the next evolution of offshore infrastructure, similar to how oil and gas first exploited deepwater resources decades ago.

The company has built a prototype, a proof‑of‑concept unit has been sent to Norway, and their first commercial project is planned in the UK in 2028.

They are also part of the NVIDIA Inception programme, which supports early‑stage AI hardware startups.

Highlander Hailanyun

Highlander Hailanyun is the developer of China’s first commercial wind‑powered underwater data centre, located off the coast of Shanghai’s Lin‑gang Special Area.

It is currently the largest and most advanced subsea data‑centre deployment in the world, running 2,000 servers at 24MW capacity.

They have built subsea data‑centre capsules that sit on the seabed and run AI workloads using offshore wind power, deep‑sea natural cooling and optical‑electrical composite cables.

Together, these components create a fully integrated offshore compute system offering power, cooling and servers in one underwater pod.

The capsules sit 10–32 feet below the ocean and are dry inside, as well as oxygen‑ and dust‑free, to protect from corrosion. They situate near wind farms of over 50 turbines, which deliver electricity through optical‑electrical cables to avoid grid losses. This provides 95% green power.

Again, the ocean cools the servers naturally, as deep seawater stays around 15 degrees year‑round.

Copper pipes circulate coolant through the capsule walls, transferring heat into the ocean. This eliminates chillers, fans and freshwater use.

In addition, the pods are maintenance‑free, having been built with redundant servers and a nitrogen‑rich atmosphere.

Highlander Hailanyun is part of Beijing Highlander Data Technology Co., which was founded in 2001. They are backed by the National Green Development Fund, China’s sovereign green‑tech investment vehicle.

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