Copyright: The BBC In a race to find out what great pressures confront life in our ocean, the team continue their mission across our blue planet to investigate the effect human impact has had on our marine life. As the sun rises over the Great Barrier Reef, Liz Bonnin joins scientists live to find out how temperature rises and plastics are affecting the reef and putting the future of the planet’s turtles at risk. In a dramatic manoeuvre to capture coral spawning we follow an ambitious attempt to restore the reef through IVF. 15,000 miles away Steve explores an eerie Caribbean wreck, during a live dive, in search of a super-sized fish that is upsetting the natural order in the shark’s home waters. Continuing his journey down the Baja peninsula in Mexico, Chris is on a quest for ocean giants, are this year’s blue whale families in good shape? He helps researchers deploy a ‘snotbot’ to make their diagnosis. 

Out in the pacific the crew on board expedition research vessel, Atlantis, explore the mysterious world of the deep ocean. Their findings will help them assess the health of ocean and find out how our actions are impacting the deepest, darkest, depths.

Copyright: Mark McClean Mexico’s Sea of Cortez is abundant and rich with marine life, a spectacle that Chris Packham is witness to, live, from land, sea and air. But as marine life around the world is poised to embark on epic journeys across the planet’s vast oceans, the Blue Planet Live team discover how ocean traffic, over-fishing and noise pollution could impact these sea faring commuters. Steve, Chris and Liz will be rolling up their sleeves with scientists to further understand the importance of migrations, long and short and understand how human demands on the oceans impact these wild journeys. Exciting live encounters with remarkable wildlife and biologists on the front line reveal the steps being taken to solve many of the issues that marine life face on its journey around our blue planet.

Liz joins scientists on the Great Barrier Reef to witness baby turtles taking their first steps and carries out a weigh in on young shearwater chicks. Steve finds himself surrounded by stingrays as a team attempt to ultrasound some pregnant females and Chris hooks up with whale experts in search for the return of a long lost visitor to these waters, the sperm whale. Live cameras will be standing by on research vessel Atlantis as deep-sub Alvin resurfaces with some vital signs from the abyss.

Copyright: Mark McClean In the final programme of this week long ocean health check, we find out what the future holds for the next generation of marine life and how we can help. The team looks at how scientists across the world are embracing technology to find solutions to the pressures faced by wildlife at sea. In Mexico, Chris is at the end point of his journey, the southern most tip of the Baja peninsula, to uncover the secret success of humpback whales. He joins a team deploying an innovative listening in device that unveils some extraordinary whale behaviour. As night turns to day we join Liz live in Australia as she tunes in to an underwater dawn chorus and is captivated by fluorescent corals that light up the reef. She also witnesses tiny turtle hatchlings run the gauntlet of predators ahead of their epic migration. 

Over in the Bahamas, Steve prepares for the final and most challenging live dive of the week. To understand more about hammerhead sharks and the journey that they will make when they leave the Bahamas, he has his most dramatic underwater encounter yet with a final live dive, then he’s on the shark run with scientists counting one of the biggest gatherings on the planet. On the open ocean our expedition vessel reports back with exciting, never before seen discoveries that the latest technology has brought us from the deep as the latest images arrive from submarine Alvin.