Just a little less than two decades ago there was only a handful of freedivers that were capturing moments underwater that were focused on large marine life. Aside from the Nikonos V, u/w cameras were bulky, expensive, and did have the high resolution as they do today. And freediving was just starting to go through a revolution and become more popular.
One of those freedivers / photographers is Scott Campbell. While I am not sure what gear he uses, all his photography is black and white and his subjects include sharks, whales, pelagic fish among others. I remember seeing his images in the early 2000s - the ones that struck a cord was that of a oceanic white tip (he was doing it before it was "in"). His photographs are raw, rough, yet beautiful - a direct result of the ocean he mostly dives in - The Pacific.
The fact that Scott spent 5 years competing on the US Freediving Team and set numerous records for depth and duration have worked in his favor - being comfortable in the ocean have allowed him to approach animals in ways that a SCUBA diver could never.
Have a look at his gallery / website: http://www.on1breath.com
Scott definitely was a trail blazer...
Scott Campbell freediving with Oceanic White Shark. Photo by: Unknown