Is their a purpose for the scuba helmet?

You can breathe underwater.
That's how you get to the underwater area in the old map. I don't know about the new map.

 

The scuba helmet comes in handy when you kill someone in deep water, and you want to search through the loot without having to keep coming up for air. Aside from that and what TBG said, I do not know of any other use for it.
I guess you could be MLG and go to nether with it on and get some kills. Would be a pretty cool challenge. That would not serve the purpose of the scuba helmet however.

 

Head north, it's at any zone 5+ I believe.

 

Since you asked if there's an underwater area for the scuba helmet, there is one. If you check one of Lord_Roke's early WarZ vids, you can see him traveling by boat some distance away from the island and using the scuba helmet to check out this underwater city.

 

#prayers

 

I'm not sure about this but you can hardly shoot underwater because you can't aim in the water nor can you see so clearly. The scuba helmet can be a good hiding / getaway item in my opinion.

 

on 6 - 10 its a underwather city thats zone 4 and dean you have to breath and if you kill some 1 in wather and you want to loot it so yea

 

Yes, like others have said it is to breathe underwater but most of all there is loot under some waters

 

You breathe underwater, simple as that