SpaceX recently acquired two oil rigs, Phobos (formerly ENSCO/Valaris 8500) and Deimos (formerly ENSCO/Valaris 8501), and is currently modifying them to serve as floating spaceports for Starships.
NASASpaceFlight.com article: https://www.nasaspaceflight.com/2021/01 ... paceports/
Wikipedia article: https://en.wikipedia.org/wiki/SpaceX_fl ... h_platform
WAI video with renders: https://www.youtube.com/watch?v=m749iC9a2g0&t=802s
Floating Starship spaceports
Render of the Deimos floating spaceport:
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