They could be: https://en.wikipedia.org/wiki/Submerged_floating_tunnel https://en.wikipedia.org/wiki/Submerged_floating_tunnel Which btw. could enable a whole

They could be: https://en.wikipedia.org/wiki/Submerged_floating_tunnel https://en.wikipedia.org/wiki/Submerged_floating_tunnel Which btw. could enable a whole bunch of other nice to have things, out there, on the high seas. Global HVDC grid. Communication lines. Pipelines of all sorts. Fish farms. Floating towns at the nodes...Resorts...Casinos...Stock Exchanges...Navy/Coast Guard/SAR bases, research hubs... Just need to grow that stuff responsible and sustainable. Dunno. Genetically modified 'Turbo Coral', or some 'shrooms' doing in-situ utilization of microplastics? Imagine the possibilities...(Hyping the loop here, harr harr!)