I’ve discussed the MARS project here before. To recap its 32 miles of cable, both power and ethernet, running from the shoreline under the seafloor to spot at about 900m slightly north of Monterey Canyon. There a hub exists where various instrument packages can be plugged in. Those then can send back data in real time which I can access on my desktop while drinking my morning brew.
Below is a nice little audio and photo montage KQED did about the project.