DREDGE

This one is easy to get once you start the DLC. All you have to do is get your insanity (the eyeball) to max making it red and swim through the oil (the black substance that spawns throughout the map) and wait for a large oil-covered monster and simply swim away or use the Banish ability within a few seconds you'll get the achievement. I tried the Banish and it didn't work, but using the speed boost I got it so if anyone wants to confirm if the Banish work let me know and I'll edit the guide.

I was unable to unlock this until after I activated the rig's defense; if you find yourself driving around the oil and only seeing the tentacles like I did, continue the DLC until you activate the defenses then attempt to find the Goliath in an oil puddle. I simply evaded the tentacles a time or two, the toothy monster showed up, then used haste to dodge it.