Let's imagine ...
The Earth is only a small part of the ocean that comes to the top. The fact that a person can not spend a long time under the surface of the water does not change anything. We can only walk on land on land, while in water we can move in all 3 directions. That is, in the ocean we are dealing with a volume, and not with a plane as on land.

Thus the inhabited world beneath the surface is much larger than its land neighbor. And this world is almost unexplored. Although, of course, the damaging effect of mankind is largely present there.
And to see all this in its original form you need to get very far. It's good that such places still exist. For example, like this part of West Papua.
Where the corals are almost not the effect of bleaching (discoloration). And at the bottom do not lie bottles and bags.