Irminger is a family name originating from Switzerland and now with relative worldwide distribution. You can see on this map from surname.io that as of 2014 this particular database had registered Irmingers at the highest frequency and density in Switzerland (138) followed by the United States (123) then drops down to 14 in Denmark, 17 in England (lower density than in Denmark), a few others in Europe, five in Australia, and one in China. Irminger is ranked as the the 895,535th most common surname in the word. 1:2.3 million in the United States and ranked at 172,735 most common.
I don't know how accurate the database really is. I would think that there are more Irmingers out there but I have only ever known fifteen Irmingers, and five have dropped the name due to marriage. There are other Irmingers that I've seen on online, and in fact someone created an Irminger Facebook group.
There is an Irminger Sea and an Irminger Current both named after Danish vice-admiral Carl Ludvig Christian Irminger. Ahh if only I could say I felt the call of the sea in bones, but alas, I'm connected by name only.
Irminger is quite possibly derived from Ermengarde? I am relatively fresh to the scene on digging into the history and stories here, so I may be wrong and I'll update this when the time is right if I learn anything more concrete. According to a potentially shaky source and source2:
Ermengarde or Ermengard or Irmingard or Irmgard is a feminine given name of German origin derived from the German words "ermen/irmin," meaning "whole, universal" and "gard" meaning "enclosure, protection". Armgarð is a Faroese version. It is the name of various historical women...
So anyway. This page can be a brief tribute to the Irminger name.