Why haven't we colonised ocean floor yet?

same reason i ain't fucked ur mom yet
cost benefit
it's nature

presumably due to water pressure/the bends user

>Subsequent investigation by forensic pathologists determined that Hellevik, being exposed to the highest pressure gradient and in the process of moving to secure the inner door, was forced through the 60 centimetres (24 in) diameter opening created by the jammed interior trunk door by escaping air and violently dismembered, including bisection of his thoracoabdominal cavity, which further resulted in expulsion of all of the internal organs of his chest and abdomen, except the trachea and a section of small intestine, and of the thoracic spine. These were projected some distance, one section later being found 10 metres (30 ft) vertically above the exterior pressure door.
No thanks.