I apologize in advance if this has been posted before, so just keep the flaming to a Minimum. Thanks.
Well when you enter the 'pipe' that takes you into Coilfang Reservoir, look for this "Crack" in the pipe. Swim through and you'll be inside a sort of... unfinished area. Not sure if there's anything worth seeing in there, since I was busy at the time. Enjoy!
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