Nathalie and Jim get up close and personal with tiger and lemon sharks, trying to get the best footage while taking care not to disturb or excite the dangerous animals.

The team's divers conclude their filming and come back to the surface unharmed. We learn more about current developments in the prevention of shark attacks.

In this episode, Doc Gruber and a colleague are testing a shark repellent. If effective, it could help save the lives of divers, swimmers and surfers all over the world.

Here's some more stunning underwater footage. This time it's hammerhead sharks and stingrays, a wahoo and some striped eels, all filmed near the Cocos Island in the Caribbean. Take a look!

Samuel Gruber's team films white-tipped sharks and barracuda feeding at night off Cocos Island. Enjoy!

The great white shark and killer whale are both infamous marine predators. Normally they leave each other alone, but one day, biologists off the cost of California witness something unprecedented.

Several boats converge near the largest of the Farallon Islands when killer whales are spotted. But what they think is a young killer whale turns out to be a great white shark.

Here we see a simulation of how the attack happened, and find out what effect it had on the population of great white sharks around the Farallon Islands.

How do sharks communicate? Particularly, how would the sharks around the Farallones all know exactly when to evacuate? Scientists who are working on "shark repellent" may have an explanation.

Although no one will ever be completely certain why it occurred, many things have been learned about both species from the attack.

National Geographic filmed South African penguins in their natural habitat. One penguin turns to crime in order to furnish the nest and keep his mate happy.

The birth cycle of kangaroos, affectionately called “roos,” is the subject of this video from National Geographic.

Within a deep and narrow cave in South Africa, paleoanthropologist Lee Berger and his team found fossil remains belonging to the newest member of our human family. The Homo naledi discovery adds another exciting chapter to the human evolution story by introducing an ancestor that was primitive, but shared physical characteristics with modern humans.

Plastic pollution poses one of the biggest known threats to the ocean and all related ecosystems. Pollution comes in many forms, and agriculture is one important key to bringing about necessary change. All of us are key players, since we all eat food.

Ellis Island, the U.S. gateway to immigration from distant lands, has been reopened to visitors, following significant damage from Hurricane Sandy. A visit there, and to the nearby Statue of Liberty, can be emotional, even for those born in the U.S.