One of the major issues with underwater photography is the possibility of flooding the housing with water and damaging the camera. I believe the majority of cases of flooding don’t occur due to some catastrophic failure of the housing (crumpling under the pressure) but rather an imperfect o ring seal due to a spec of dirt or a hair. In these cases water may trickle rather than surge inside the housing. If you’re busy checking your gauges, or you’re diving at night you may not notice the water until it’s too late. Some housings come with a built in leak detector, but for those that don’t, a quick visit to UWleakdetectors.com is a good idea. For 36 dollars you get a little bit of circuitry, velcro and some blue tack that may just save your equipment from a dunking.
With regards to my housing I checked with Ikelite and it turns out that there is a control on the housing that allows you to press the lens release button. Now this has been pointed out to them I expect this unusual feature will disappear from any future housings made for the K5.