From Hell's Heart I Stab at Thee

Okay, we just 3 manned this guy, me as a Warlock being the "tank", an arcane Mage and a feral Druid helping. You have to kite him withing 6-20 yards range, I suggest getting an addon to keep track of it (I used the built in function in stuf) and keep around 15 yards, it gives you a little go on. I think Warlocks are the best choice to tank him due to being able to keep 3 dots rolling on him while kiting, keeping you with significant threat and you can glyph underwater breathing to get a little extra speed boost. I kited him as demo using the imp. I pulled with immolate (the pull is the hardest part of the whole thing once you get it down) then I got CoE, BoD and corruption rolling on him, kept immo up with constant fel fire spam. I would pop meta whenever it was ready and use all my soulburned soul fires during those (we spent well over 10 minutes on this).

The pet choice was obvious, none of the melee pets can do anything without getting eaten (they will try to go behind him, getting themselves killed in the process), but with the imp you can have him launch 2-3 fire bolts then have him swim to you again. Extra pet management, but in the long run it is a lot of extra damage. I used my doomguard once during the fight, he got eaten after 20-30 seconds, but it's extra damage so it's all good. The Mage was swimming beside me the whole time to keep proper range, the Druid was behind or something, I dunno (he joined after we started) and I spent most of my time looking at the range monitor, the area around me (don't wanna get stuck while kiting him) and his ugly face.

There are only three importants things to remember during this fight: Let the kiter have lots of threat. Don't get in melee range. Be calm.

The first two-three attempts we messed up due to me getting nervous and ranging him, which causes him to evade and reset. After a few more tries I started getting my confidence back (I won't lie, he scared the *!@# out of me the first time I saw him) and I was working my way through a second bottle of beer, calming the nerves (no, I'm not an alcoholic). So give it a few tries, learn how to kite him and enjoy one of the most intense kites in the game.

P.S. Kiting this guy cured my fear for sea creatures. I guess it is true that facing your fears will help you overcome them.

EDIT: Spelling.

During Beta, this achievement awarded the title "Ishmael" for a very short time.

In addition, this massive creature has already been solo'ed and by a Warlock in the Beta none the less. (NERF WARLOCKS!) ;) The killing even got an official Blue comment.

Noooooooooooooooooooooooooooooo!

You will all pay for your treachery.

-Zarhym

(Source)

Herman Melville reference, specifically:

Ahab ultimately dooms the crew of the Pequod (save for Ishmael) to death by his obsession with Moby Dikk. During the final chase, Ahab hurls his final harpoon while yelling his now-famous revenge line:

... to the last I grapple with thee; from hell's heart I stab at thee; for hate's sake I spit my last breath at thee.

Read more about Moby Dikk at Wikipedia. (I am aware of the spell error of Moby's name, but the profanity will ruin the links if I use his proper last name.)