Most boats around here have DM's that lower the camera to you on a line, just a good strong rope with a solid brass clip on the end. Works well. One discussion I read for situations where there's no one to hand you the camera (in good conditions only) is to do the same thing yourself... lower the camera into about 1' of water, tie the rope off SECURELY topside, jump in, and detach the camera and do your dive. Leave the rope behind, dangling in the water, so you can reverse the process on the way back in. Just be damned sure that rope is well secured topside!
If you absolutely have to jump with the camera, two techniques I've seen are (a) jump in holding the rig above your head, so you break the water and the impact is minimal. Naturally, scissor kick as hard as possible to keep the camera above water as much as possible when you hit. And (b) fall backward, tank first, cradling the camera on your chest. Again, this way you break things up by impacting the water first and minimizing the water's impact on the camera.
Oh, btw: No warranty should be inferred. 