If you want to take your phone kitesurfing with you, or just protect it from sand and water, this waterproof phone pouch can with stand depths of more than 30m. It will also look after cash, credit cards and car keys (although not all at the same time!).
The pouch is 176mmx106mm so can hold most standard smart phones up to 6.5 inches.
The touch screen still works when the phone is in the pouch so it's ideal for emergencies and for safely taking photos in the water.