I disagree: anywhere in the ocean is easier logistics than crawler trains over land: ship it there and chuck it overboard. They do that to install oil rigs all the time (but that's more like float it there and sink it). Eg: https://www.wired.com/2014/07/dockwise-vanguard-shipping

Yeah, but now imagine the cost of putting large active electronics 4,000 meters down on the sea floor and keeping it running, and getting the data back off it... The cost of running the drill rig seen in the photos of the icecube detector would be a fraction of that.