How to get murloc costume

I have seen people have it but it isnt in the marketplace... i want it :C

What you see is King Mrgl-Mrgl's Spare Suit which is an item given to players during the quest "Surrender... Not!" by the Winterfin Tribe Murlocks in Borean Tundra. It is only available to you if you have the quest.

It should only be usable in the Winterfin Caverns area, but if you see it outside of there then the item may not have the proper limitations on it.

You could also have genuinely seen someone with the Murloc Costume in which case it was likely won from an event that Warmane does from time to time.

Got mine from an event a couple of months ago, I think it's been the only one on Lordaeron so far and a total of 40 players got it.

The quest version of Murloc costume is, at least in this server, usable throughout Borean Tundra. Since I'm not retail player, dunno if this is a bug or not.

Doesn't do much, really. You mostly can't do stuff like taking flight path in that costume. As warrior I can do Bloodrage and change stance with it curiously, but disguise drops as soon as I land a blow.

Wear it if you're doing the quest mentioned above, or if you just want to attract and entertain some fellows. Their /emotes are hilarious. Try jumping too as your toon can actually fall flat on his belly upon landing, provided you're not moving afterwards. Cracks me up all the time (this is just animation, you don't actually get stunned/rooted/debuffed if your toon 'falls:)

Now let's call Lvl80(?) Elite Tauren Chieftain and have them play 'I am Murloc' with us.

that costume disappeared when I signed up for wow and that's what I had made that story.