In summer, I usually take two 1.5-liter bottles of water in my backpack on a hiking fishing trip. I freeze one beforehand. Gradually the ice in the second bottle thaws, so the water in it does not have time to heat up. And the coolness in the backpack helps to save lunch, or to keep the fish I take home from spoiling.
![](https://zmicerfish.com/wp-content/uploads/IMG_2475-1024x768.jpg)