If you're stuck somewhere without any after-sun lotion, don't despair. There are lots of treatments that travellers swear by. Some recommend smearing honey on to the damaged skin, or covering it with slices of avocado or cucumber.
Most important, as with any kind of burn, is to cool the skin down. Ignore people who suggest a hot bath and particularly those who advocate adding cider vinegar to it! Instead bathe in cool water.
Even applying ice can help if it's not too painful. Some recommend adding oatmeal to your cold bath, saying it has soothing properties. Or, if you have them, try adding pure lavender, chamomile or peppermint essential oils to the bath. It's important to rehydrate the body too, by drinking water or mint tea, or by eating a high-water content fruit, such as grapefruit or watermelon.
If you want to buy a suntan lotion with natural instead of man-made ingredients, look for one with extracts of the edelweiss plant, which grows at high altitudes and has high concentrations of natural UV light-absorbing chemicals. In his new book, Born Survivor, explorer Bear Grylls, recommends a simple solution if caught in a survival situation without suntan cream at all: smear any uncovered skin in mud.
· Born Survivor is published by Channel 4 Books at £18.99.