I don't mean the beautifully hand-crafted artisanal chunk of frozen water currently residing in your old-fashioned glass. I mean how did ice make it's way into a cocktail glass in the first place? well, the ice chilling and diluting 19th century Caribbean cocktails originally shipped from frozen ponds in the Northeast United States.
Listen to "The Ice King", episode 198 of 99% Invisible, to hear about how the ice trade came to be, how ice was transported to (and stored in) tropical climates like Barbados, and how it eventually faded way as home refrigeration took hold in the 20th century. We take ice for granted now but it wasn't always this way.
If you're not a regular listener to 99% Invisible, you may as well subscribe and make it part of your podcast habit. It's a weekly show (usually about 20 minutes long) ostensibly about architecture and design but more truly it is, as they say "about all the thought that goes into the things we don't think about." Like how ice for cocktails came to our glasses.