https://whale-tales.org/flue-the-hybrid-whale-23-7-20/

https://pubmed.ncbi.nlm.nih.gov/32170708/

The airplane is either in a few pieces or a debris field, sunk to the bottom and very inert.

Finding one you need a sensor network which can track it in near realtime as you hunt it down. Finding the other you need to map huge swathes of the deep ocean with high enough resolution to be able to see debris.

One is not a "harder version" of the other, but entirely different challenges. It is a bit like saying "oh you can't even make a jetpack? Good luck making a fully reusable orbital launcher." Yeah they are both rockets(ocean) things but they have nothing else in common.