Underwater casings are common for dSLRs and compacts, but this is the first time I've come across a housing made for rangefinder cameras. In this case, it is for the premium Leica M8 digital rangefinder, which costs about $4,500.
This boxy case allows users to access most of the controls and is rated to be able to dive to depths of about 148 feet. However, given the complex operation of rangefinders for focusing, we wonder how well it will perform underwater.
If you have $8,000 to spare, you can get a housing, put your M8 in it, and bring the whole contraption for a dive. Mere mortals like us will have to content ourselves with waterproof compacts.