When it comes to summer, it is essential that you invest in a great waterproof mascara. Holidays and festivals really can test the longevity of your makeup. From the pool and the sea (and even the rain if you're attending a festival in England!), your mascara will face a number of tests to see how 'waterproof' the formula really is. We put 5 of our best selling waterproof mascaras to the test.