When you are in a really hot place it cam be hard to keep your drinks cool. Naturally keeping your drinks out of direct sunlight helps a lot but eventually it will heat up to whatever the air temperature is.
I remember being in India one time and it was about 40 degree´s centigrade, my water bottle was in my bag and my bag had been inside a car with no air conditioning for several hours. When i got the water bottle out and took a gulp it actually burnt my lips and throat it was so hot.
A quick, easy and simple way to keep things cool is by harnessing the cooling power of evaporation.
Get a thick hiking sock and soak it in water, put your bottle inside the sock and as the water in the sock evaporates, it will help to move the heat from your drink.
It really works, British soldiers in Afghanistan did this all the time due the ¨rustic¨ conditions and extreme heat (50+ degrees c)
For water to evaporate, it needs to be heated. Most of this heat comes from the sun and air. When you sweat, your body heat is what evaporate the sweat away and you expend excess heat in doing so which is what makes sweating such an efficient and effective cooling off system.
With the wet sock and the bottle trick, the heat of the water in the bottle will be used to evaporate the water in the wet sock. So you end up using the unwanted heat up to dry the sock and the end result is a cool drink.
It´s very simple and very effective. You´re welcome!