NEWSFLASH! Fly fishing addicts enjoy frozen cocktails from their drift boat the river. Frozen mango daiquiris sipped from Hydro Flask allowed the big one to get away. Well...not really, but I have no doubt a frozen drink would stay frozen for hours. Why do I think this? Well, one hot day I filled my Hydro Flask with ice, then water and headed to the beach for the afternoon. Wasn't especially thirsty while there so I brought it home and set it on the counter. The next day I took the still-full Hydro Flask to work, and was stunned when I went to drink. The Hydro Flask was still full of ice, from 20 hours earlier! How long would the ice last I wondered? I drank some of the water that day but left the remaining ice and water in the bottle. The following day I was astounded to find a significant amount of ice still in the Hydro Flask! Amazing, unbelieveable you say? Yes, but absolutely true. Love my Hyrdo Flask!