Navy powerplug/lightbulb socket? what is it?

[militaria360]

I've got one of these that came with some other stuff I bought a few years ago https://www.toddmarine.net/default.aspx?page=item+detail&itemcode=SYM+735.3&catlist=174100

 

I know "what it is" since it says "15A 125V 2P-G WT RECEPTACLE MIL-R-2726/47-001", but what was it used for is it the naval equivalent of a house power socket? 

[Unicorn]

 It looks like it might just be a waterproof outlet. I'd assume for exterior use. http://connectorselectrical.emilspec.com/MIL-DTL-2726-47/index.html