Resources to learn about marine life
There are a lot of marine documentaries out there. These are some that I know of:

Shark (2 episode series in 2015);
Deep Ocean;
Life in the Blue;
Ocean of Giants (Nat Geo);
Ocean Giants (BBC);
Humpback Whales;
Ocean Voyagers (whales);
The Polar Sea;
Swimming with Killer Whales;
Ocean Wonders (no narration, just under sea footage of animal behaviour);
Martin Clunes: Man to Manta;
Nature's Great Events: Diaries (a couple episodes of marine ecology);
Dolphins: Spy in the Pod (a view on dolphin activity using dolphin-shaped cameras);

I watched these off YouTube:
Alien Reefs;
The Giants of Rurutu (whales);
Mucky Secrets: The Marine Creatures of the Lembeh Straight;
Reef Life of the Andaman;
Secrets of the Australian Ocean;
Oceans of Contrast (spends a lot of time on life on land revolving around the ocean, but there's reef life as well);
The Incredible Glowing Creatures of the Deep Sea: Documentary on Bioluminescent Sea Life;
Documentary on Coral: African Wonderful Coral Reef

Conservation type documentaries:
Sharkwater;
Mission Blue;
Chasing Coral;
Blackfish;
Sonic Sea;
A Plastic Ocean;
Shark Men (If you like reality style television series. They capture, tag and learn about sharks to protect them)

If you want a more in-depth resource for learning, you can also YouTube search "marine biology lectures"