Oceans cover more than two-thirds of the surface of the planet - yet they are still not fully understood.
The world's oceans play an important role in the Earth's climate system, and millions of people depend on them directly for sustenance. People also traverse the oceans, and use them to transport goods. Yet the world's oceans are in trouble, as warming and acidification take their toll. They've also become a garbage dump for the planet, with consequences for marine life.
This week on the show, we visit the Pescadero Basin off Mexico's Pacific coast and shipwrecks in the cold waters of the Baltic Sea. Exploring the oceans – from tube worms to sea turtles – we look at the rich life they sustain. We'll also be asking what impact we humans have on our seas.
One of the most pressing issues of our time is the impact of single-use plastics on our lives. Last month, the European Parliament supported a wide-ranging ban on single-use plastics - in an attempt to counter pollution from discarded items that end up in oceans and landfills. Now, environmental group Greenpeace says the world's biggest food group isn't doing enough.
Eight million tons of plastic end up in the ocean every year. One forecast suggests that by 2050, there could be more plastic in our oceans than fish. British yachtswoman, Emily Penn, has become a tireless campaigner against ocean plastics. She now raises awareness on the topic and conducts scientific research in some of the most remote parts of our world.
Huge amounts of plastic waste end up in the oceans every year. Now the European Union has taken action - by getting a step closer to banning plastic plates, drinking straws and other and other disposable plastic products. EU lawmakers agreed on the measure in Brussels on Tuesday.