Subsea installations are becoming more and more important in the Offshore industry, be it Oil & Gas or Renewables. That applies both in shallow and deep waters:
https://www.offshore-mag.com/subsea/article/14188896/aker-solutions-awarded-loi-for-kristin-sr-subsea-trees
Even subsea gas compression units are in operation in deep cold water off the coast of Norway since 2015:
This requires high capacity and reliable electric drive systems that can operate in deep water:
https://www.offshore-mag.com/subsea/article/14187012/onesubsea-compressor-proven-to-work-with-abb-subsea-drive
As floating windmills in deep water becomes a reality, Subsea Power substations, subsea power distribution and long subsea high voltage DC cables to send the power to it’s consumers are also being developed:
https://www.onepetro.org/conference-paper/OTC-30766-MS
Vessels to install and maintain these installations are therefore in greater demand than those who service fixed and floating installations.
Here is one of the latest to join the Subsea 7 fleet. Subsea Vega: