Secure Seabrush

Just kill a Alliance Sea-Scout and you will get the quest.

This is one of those quests that can easily be missed if you aren't looking for the mobs in the right area. In fact, unless you run the Alliance version, where it is far harder to actually miss out on said quest, you might not know this one exists.

If you've done the Alliance quest and are looking for the equivalent Horde-side, you might not be at the right altitude. Keep heading down if you can't find any of the quest mobs. You'll likely find some very close to Underlight Canyon.

Just remember that if you're going to use a /target macro to hunt for the targets that it will detect them quite a few "levels" above where they typically are. If you're still seeing thick forests of kelp, you're not far enough down.

The mobs themselves are easy. They can poison and use an immobilizing/"stun" move that does damage called "Strangle Rope", but the damage it does is negligible by this point.

For those using quest completist, it appears that there are two quests with the same name, 1 that starts from killing the mob, and one given by a quest giver.

I know of no way to complete both, so you may have to shift-click to remove the name of the quest that you didn't complete from your quest completist list.