This one was okay. Here's the thing. My favorite documentaries don't use up time to show or talk about the human explorers/scientists unless something super unusual happens to them during filming. This is a doc where it's like 50/50 the biology / the biologists. There's a lot of process. There's almost always the divers/scientists in the shots. It is interesting to learn about the diving and how the research trips are conducted and funded (by letting tourist divers hitch a ride for a fee,) but my favorite documentaries focus entirely on the animals and avoid showing humans as much as possible. If you like seeing the humans study the animals, this one is good for you.
Aside from that, this one has to do with large rock formations in the ocean and how that forces the ocean currents to bring plankton up and concentrate them which attracts a lot of life. The rock features also provide homes to coral and shelter for sea creatures. The plankton attracts lots of filter feeders like whale sharks and giant manta rays, so they are featured heavily. There's also a lot on schools of fish, their behavior, and the predators that hunt them. Some porpoise activity as well.
There is also a short sequence where a submersible explores the deeper water around one of these formations. Mainly between 200-500 meters. They find a Prickly Shark which is a kind of deepwater shark that's rarely ever been filmed.
