Besides outer space,  we humans also like to explore the ocean.   Since three-quarters of the Earth's surface is covered by oceans,  there should still be a lot of resources that can be developed,  as well as many undiscovered organisms living there?   Maybe there are extremely large fish or even extraterrestrials living on the seabed.   They definitely wouldn't be disturbed by humans there.

If the technology exists,  it would be pretty nice to build a residential community in the ocean.   However,  there are many animals and plants in the sea that do not exist on land.   They far outnumber those living on land,  plus there are still many undiscovered species.   It may not be easy to live in harmony.   Scientist often say the land on Earth will eventually sink beneath the sea.   Will that be the end of human life or will we evolve into amphibians?