This humongous power-plug is a MacArtney Wet Mate Connector that allows undersea cables for floating windmills to be connected below the water's surface.
But mostly I like it because it is has those outsized, Tonka-toy yellow rugged good looks.
MacArtney's wet mate connector shortens the time needed for connection and makes it possible to operate in waters with limited time windows. This is particularly important for renewable energy devices where changing tides or wave action are often associated with marine renewable deployments. The MacArtney 11kV wet mate connector provides safe and reliable connection to the power grid and addresses a number of fundamental challenges in building and maintaining marine renewable installations. Development of the connector was funded by ETI and testing witnessed by DnV (Det Norske Veritas).
MacArtney 11kV (7.6MW) Wet Mate Connector | MacArtney [Archive.org]
MacArtney 11kV (7.6MW) Wet Mate Connector [MacArtney]