system
Given the following post, respond as if you're commenting on Reddit:
human
Why haven't we completely discovered ocean's deep creatures yet?

I have heard so many times that most deep water creatures are yet to discovered, why is that so? We have discovered so many things in space through telescopes and space programs and yet our own ocean's depth is unknown. How hard is it to create a device that can scan or image deep oceans?
gpt
It is perfectly justified that we yet have to describe an enormous amount of species from the oceanic deeps.

Compare with Earths surface: we have been categorizing and describing species there for millenia. And yet we still are not done, as we find new species every year.

In comparison, the océans are three times as large as the continents, and far less accessible. Benthic areas outside the continental shelves have only begun to be looked at within the last 75 years or so (beeing generous). Even today they are barely accessible at all, despite the increased use of ROVs and minisubs. You can't caracterise species through bulk large scale long distance viewing (that would be akin to trying to define the species of a rainforest from high-altitude fly-bys - you are going to miss out on most and won't get enough detail for the rest): you have got to get there and see/sample the critters first hand.