Billia Croo, Stromness, Orkney, Scotland
#00219
Case study of
#00212 Relocate compute into submerged or floating offshore modules cooled by seawater
Implementer
Microsoft Research, with the European Marine Energy Centre
Timeline
Jun 1, 2018 – Jul 1, 2020
Location
Description
Microsoft deployed a sealed, nitrogen-filled cylindrical vessel containing 864 servers to the seabed at 117 feet off Orkney, powered by the islands' wind and solar grid, and retrieved it two years later. Phase 1 had been a 105-day proof of deployment off California in 2015.
Microsoft did not proceed to Phase 3 or any commercial deployment. In June 2024, Noelle Walsh, head of Microsoft Cloud Operations and Innovation, stated: "I'm not building subsea data centers anywhere in the world." Microsoft attributed the reliability improvement to the dry nitrogen atmosphere and the absence of human technicians — neither of which requires immersion — and carried those learnings into land-based sealed-rack designs.
Metrics
5Funding
Lessons learned
- The reliability benefit came from the sealed nitrogen atmosphere and the exclusion of human technicians, not from being underwater. Both are reproducible on land at far lower cost, which is the most transferable finding of the entire programme.
- A technically successful demonstration is not a viable product. The programme met its stated goals and was still discontinued because serviceability, cost, and regulatory exposure were not what the experiment measured.
- Deploy-sealed and retrieve-whole is incompatible with a three-to-five year accelerator refresh cycle. Any subsea proposal for AI compute has to answer this, and none currently does.
Sources
3Documented Jul 28, 2026