Note its good to experiment living underground & under the ocean to prepare for outerspace colonization.
Note it has been predicted by scientists that all coastal cities & towns will be under 30 metres of water in 500 to 1000 years time due to global warming or the sun expanding into a red giant, therefore robots will have to farm the landmass's & mining & manufacturing can also be done by robots on land & under the ocean as well.
Its possible that the entire population of planet earth can live in a mega city about the size of texas under the ocean & trains can transport goods from land to this under ocean city which will be probably located on the coast. Probably the better option is to waterproof coastal cities & towns so they can exist under water.
Sydney should start to be converted into a under ocean city now as it will be under 30 metres of sea water in 500 to 1000 years time.
Get yourselves some scuba gear, you will need a air compressor & air hose to fill up your scuba tank with air, water proof your house so it can withstand underwater conditions. What about transport ? Well this could be a tricky affair, boats look like the easiest option, however underground tunnel technology like the Sydney Harbour Tunnel might be common place.