The Waterproof Case for the KeyMission 170 from Nikon allows you to use the KeyMission 170 Action Camera underwater in depths down to 132 ft for approximately 30 minutes. The camera is capable of being used in depths down to 33 ft without any case, but this case lets you dive almost five times deeper.
The case also features a compartment for keeping a spare battery (not included). The spare battery doesn't connect to anything but can be used to replace your active battery when it runs out of power.