If you're travelling to very hot countries, think about protecting your kid against the sun all the time, even while swimming. These cute tops are super comfy and have a sun protection factor 50+.
SPF is a rating given to clothing to indicate how effectively the fabric blocks ultraviolet radiation (Ultraviolet Protection Factor). A UPF rating of 25 means that only 1/25th (or 4%) of the UV radiation can penetrate the fabric. The lower the rating, the least protective it is. To be effective, a garment should hold the UPF50+ rating in order to filter 98% of harmful UV rays.