As dozens of top surfers from across the world arrive in Nazaré to train and prepare for a major big-wave competition, Garret McNamara continues to struggle with his physical injuries and mental preparedness. He knows he is not ready to surf in the competition but seeing the other surfers makes him consider competing anyway. Garrett also has misgivings about the state of safety plans at the competition, and tries to convince the organizers to beef up their plans.

The day of the Nazaré competition has arrived, and Garrett McNamara decides not to compete but instead support his long-time friend and teammate Andrew 'Cotty' Cotton. The competition does not go smoothly, with a major accident that has secondary effects on Cotty. After the competition, Garrett tries surfing at Nazaré again and realizes that can resume big-wave surfing. The episode concludes with retrospectives from a number of the surfers who appeared on various episodes throughout the season.

Science may soon make the dream of traveling to Mars a reality, but how will we live once we get there? How will we manage our basic human needs of food, water, and shelter on a planet known for its barren surface conditions, high radiation levels, and toxic dirt?

Antarctica is the most hostile of all earth’s frozen worlds. Yet even here, amongst some of the most challenging conditions on the planet, life finds a way not just to survive, but thrive.
Our journey begins at the far edge of the continent, on its far-flung sub-Antarctic islands. Here we meet king penguins that, to feed at sea, must face the danger of ferocious leopard seals lurking in the shallows. On another island, we witness for the first time male Antipodean wandering albatross partnering up with each other as the females in their population are disappearing due to fishing activity.
Heading towards the continent of Antarctica, we traverse the roughest seas on earth - the Southern Ocean - where we find the rarely filmed Antarctic blue whale, the largest animal to have ever lived. At the edge of Antarctica, the sea is so cold that it freezes over, creating a vital ice platform for a mother Weddell seal to raise her precious pup. Still, she needs to protect him from aggressive males.
In spring, the coast of Antarctica is free of snow, drawing in thousands of breeding chinstrap penguins. Stones are at a premium to build their elevated nests and protect chicks from meltwater. But stealing is commonplace, and to make matters worse, with climate change we find chicks today shivering with hypothermia – a warming Antarctica means increased meltwater. Other residents are facing an uncertain future too, including wave-washing killer whales. We discover that their favourite prey, Weddell seals, are now harder to reach, so instead they are resorting to targeting much more feisty prey, including leopard seals, an apex predator in its own right. This dramatic encounter has never been filmed before.
Travelling into the interior of the continent - into the frozen heart of Antarctica - we find great surprises. This is one of the most volcanic regions on earth, and one of the driest. We reveal unexpected sand dunes, hidden in a rare ice-free valley. Then, on the exposed mountain tops, sticking out from the otherwise ice-covered interior, we find tiny snow petrels, which raise their chicks further south than any other bird, and defend their territory by projectile vomiting!
The greatest revelation lies deep in the interior, beneath the surface of an ice-covered lake, where we discover ancient alien-like structures - giant stromatolites - built by primitive lifeforms. If life can make it here, in the extremes of Antarctica, it raises the possibility that life can exist elsewhere, including in the frozen lakes of distant planets.

A female Phosphorosaurus hunts lanternfish under the ocean's moonlit surface. Hesperornis hunt for fish until they themselves are hunted by Xiphactinus. A Mosasaurus hunts a group of Tuarangisaurus. Nostoceras hatchlings are at the mercy of the tides and juvenile Pyroraptor. The young Nostoceras that survived find themselves among Baculites and Diplomoceras in their new seagrass meadow home. A pod of Morturneria sift the muddy seabed in search of food.

Mars is infested with robots, orbiting the planet and roaming the Martian surface on a mission to uncover its secrets; now, Perseverance joins this dedicated group of machines to uncover if there is, or was ever, life on the Red Planet.
Our neighbor, Mars, fascinates us. It's a planet that is similar to Earth but with some big differences. Mars is rusty, dusty, frigid, and frozen. Past missions suggest that Mars was once a very different world. The Mars we see today has completely changed from the Mars of a few billion years ago. Without a time machine to explore ancient Mars, we employ a team of high-tech robot investigators, an entire fleet of robotic spacecraft exploring the planet. Working together, they dig into Mars's past to answer the ultimate question -- did Mars once have life?