The Griffin Survivor + Catalyst waterproof case (US$69.99) is said to keep your iPhone dry up to 3 meters deep in water and protect your iPhone from drops from a height of 2 meters or less.
On a day-to-day basis I don't use a case for my iPhone. However, there have been plenty of occasions when I've wished I did use one, so as not to worry about protecting and shielding it in certain situations, like when I'm at the beach, hiking or camping etc.
Design
The Griffin Survivor + Catalyst (GSC) case has TPE shock-absorbing bumpers, a PET-integrated screen cover, a silicone O-ring to seal the case together and keep water out, and a polycarbonate frame. Though light, it feels sturdy -- especially with an iPhon