i know, i was impressed, which is why i tried to figure out which camera it was after i rented it. i'm pretty sure it was a sea & sea housing with a generic/unlabelled ricoh point-and-shoot inside (i think it was a dx5000g housing with a ricoh caplio GX? inside). the housing had an external flash on an adjustable arm, as well as an optional wide-angle lens you could screw on (you can see the wide-angle effect in the 3rd to last shot).
i found that it helps to shoot either in shallow water, or if in deep water, shoot close-up using the flash, since when you get deep down the water has already filtered out most of the red spectrum. if you do shoot wide shots deep down, you need to adjust the color balance in photoshop or a similar program afterwards to bring the reds and yellows back.
honestly, i think the adjustable flash and getting up close to the subjects (along with some post-processing) made a huge difference. it just goes to show that the camera is only part of the equation (for a different demonstration of this principle, see the iphone macro photos in one of the other threads)