Check out this beautiful video shot by Tony Land, using the Nauticam NA-GH4 housing with the Panasonic GH4.
This is a deep Cenote... over 300 ft, and it looks amazing. The rooms are huge, and it takes a lot of light power to get enough light to get these shots. The primary lights used here are the Keldan LUNA 8, and Tony also used the NEX NEO 2000 for low intensity fill light. BTW, we'll be featuring this video at the 2014 DEMA show in Las Vegas in a couple of weeks. Definitely plan to stop by the booth (#) and check it out on a real 4K TV.
The video is shot in 4K, and Tony has made use of the new 4K capability of YouTube to present it. Even if you don't have a 4K monitor (yet!), make sure to play it back on the highest resolution you can, and at full screen; it is well worth the look.
For more info about the dive and The Pitt, checkout out the blog post from AddHelium.