As stated in one of the most popular sci-fi books of all time - "The Hitchhiker's Guide to the Galaxy" - one should always bring a towel. You never know when you will need it and it has many uses during your travel, whether its at the beach, on a picnic or even the Gobi desert.
You can use the towel as its intended use of drying yourself after a shower. Or in an emergency, you can use it as a clean surface for all your supplies. In the Gobi, you can dab it in water and use it as a cooling "pack" on your neck and shoulders during your trek. This is not all, there are many other uses towel has during an emergency. So do not forget to pack a towel. Its light and doesn't take much space in your bag.