Harsh weather has the potential to lead to delays, meaning that you should also take along sunscreen of at least SPF 15 or higher, as well as sunglasses, and of course, rain macs for if things go the other way. Sat nav on your phone isn’t going to work when you’re out in the wild, so navigation tools are the absolute first things you need to stock up on. Obviously, maps are a must and can be easily folded down to slot inside your pack.