Nothing you SEE - in fact hell of a lot happens down there that effects us; just in ways so indirect we don't even realize it. Undersea volcanos and eruptions forming new land masses (however small) causing the tectonic plates to shift (earthquake anyone?). Overfishing/hunting/harvesting can lead to extreme losses of key species allowing some species' (like whatever the key species fed on) populations to explode without check (which leads to even more problems) and other species (like predatory ones) to search for alternate food sources (one shark to another: I hear the coastlines are filled with clumsy, bad-swimming mammals in brightly colored clothing this time of year). Not to mention all the damage done by pollution, illegal dumping of wastes, and the pumping of oil. In short, quite a lot happens underwater and sooner or later the problems will come back to bite you in the rear. The reason they don't show these types of issues in the comics is simply because they are indirect in effecting the human race a.k.a. readers have short attention spans and the writers risk boring them by taking the time to show the numerous steps detailing exactly how the ocean's problems will come back to haunt the human race.
Aquaman could do quite a bit if he chose to - I'd like to see how many fishing boats survive being rammed by whales (the largest creatures on Earth), how many subs wouldn't implode after being dragged to the sea's bottom by giant squids, and how many people would continue to visit the coast if every manner of sea life from jelly fish to crabs to seals to sharks attacked them if they so much set one toe in the water.
So suddenly Aquaman is an omniscient sea god? Also, you seem to not know how large submarines are relative to actual giant squids.
Again, my point isn't that Aquaman's powers are or aren't lame. My point is that nothing happens in the ocean. Except, like, piracy and illegal dumping and such, and Aquaman's fairly overqualified for that.
1) I was being sarcastic about Aquaman being an omniscient sea god. I was trying to get across that he'd have to be to do all those things. 2) You honestly think a giant squid can drag down a submarine? Do you know how big actual giant squids are?
I do at least sign them usually, but some were originally created and posted by me anonymously, and with not much thought given to how a viewer would find me; and I've only taken ownership here retroactively, so to speak.
A gigantic squid-god creature? 'Well, yes, Aquaman, but he's very dang-' OUTRAGEOUS!!!
(a few hours later)
So Batman, want some cheese? 'Sorry, but duty calls.' Suit yourself! Cthulu, pass me some cheese will you? (a tentacle flickers, and the cheese telekinetically flies to Aquaman) Fantastic, my new chum!!
Batman: "Ok, seriously Aquaman, how is that going to help battle the Clock king and his war time army?" Green arrow: "Yeah, seriously, unless you're little buddy here wants to tangle it's coils in the tenacles." Aquaman: "Don't worry, I'm sure nancy here will sort something out." Cthullhu: YOU'RE SOULS BELONG TO ME, PUNY MORTALS!!!!!!!!!!!! (silence) Green arrow: "Who needs a change of underwear?" Clock king: "me!"