THERE’S something truly extraordinary about being hundreds of metres down in the depths of the ocean in a tiny submersible, surrounded by sharks.
But add to that the fact that you are hundreds of miles from civilisation and that the swell is suddenly threatening to smash you against the rocks, and things suddenly get a whole lot scarier.
It sounds like a scene from Jules Verne, but this is a modern-day voyage of discovery with natural history presenter Liz Bonnin following in the footsteps of Darwin in the remote Galapagos islands, 600 miles off the coast of Ecuador.

UNDERSEA WORLD: Liz Bonnin survives an underwater scare [PICTURE: BBC]
Well, not quite footsteps because Darwin never got this far under the waves. But the three-part BBC documentary series Galapagos had access to the most sophisticated underwater technology, permitting the sort of undersea adventure that Verne could only have dreamed of back in 1870 when his classic sci-fi adventure novel was published.
Not that the cutting-edge technology makes this in any way an easy excursion for celebrity biologist Bonnin, the French-born, Irish-educated presenter tagging along on a pioneering scientific expedition hoping to assess the survival prospects of some of the hundreds of unique species which populate the chain of 13 islands.
Two centuries on from the historic voyage of HMS Beagle, the aim is to explore the ocean depths, journey into volcanic craters and probe ancient forests in search of clues that could unlock the mysteries of these islands and their unique wildlife.
Like Attenborough’s Blue Planet, this is an adventure on a grand scale, as indicated by the portentous and cliché-driven two-minute introduction, which makes much of the fact that scientists know more about the surface of the moon than they do about the ocean depths and pulls in plenty of predictable lines about diving into the unknown on a voyage of discovery.
But if the intro feels a little overblown, we can forgive the documentary makers that self-indulgence once we have actually seen what’s in store for our intrepid heroine.
It’s easy to shrug off talk of dormant volcanoes and life-threatening currents when you’re sitting safely on your sofa at home, but although cheery Liz doesn’t dwell too much on what could possibly go wrong, in the second episode we share in her horror first hand when things start to get fraught under the waves.
We have already met upbeat and experienced submersible pilot Mark “Buck” Taylor earlier in the series and had our first taste of the amazing underwater world that can be accessed in his formidable eight-ton Triton submarine during the Blue Planet series.

DANGEROUS WATERS: exploring the reef beside Darwin’s Arch [PICTURE: BBC]
Buck himself has spoken in the past about his awe for the Triton’s abilities: not only can it undertake dives of up to 12 hours on occasion and reach depths of 1000 metres, but it can film a crab the size of your thumbnail in extraordinary detail.
It’s a machine which has been deployed in numerous scientific expeditions over the years, capturing the first ever footage of the giant squid in its natural habitat in 2013 and being used in a landmark series about the Great Barrier Reef with Sir David Attenborough in 2015, as well as Blue Planet II, which became the most watched UK series of 2017.
It’s clearly an honour to be one of the two passengers joining Buck on his descent into the deep and he does have that reassuring seen-it-all-before nonchalance of the expert which helps to put you at your ease.
But whereas last time we saw Liz’s unbridled joy over starfish, seahorses and coral winning out over sheer terror, this time the threat of impending doom is a lot more imminent and real: perhaps not quite what the Countrywise host envisaged when she embarked on the mission.
It’s all very well plunging into murky ocean depths that have never before been studied by science, posing wonderful questions about why hammerhead sharks school in masses and what sun fish actually do when they are underneath the ocean’s surface.
But when the ebullient Buck stops talking, you lose communication with the ship above and the currents start driving you towards the rock wall, you know it’s time to start worrying.
“I’ve had a few wildlife experiences where you get a sobering reminder of the power of the planet,” Liz said of the incident later in an interview for the Irish Examiner.
“There was this massive wall of soupy, opaque dark green water heading straight for us, and we were trying not to crash into the other submersible. The two of us were just spinning around in these currents like we were in a washing machine.”
Back on dry land, Liz sets off in search of rare pink iguanas and giant tortoises, flightless cormorants and scaly marine iguanas.

FOOTSTEPS OF DARWIN: Liz explores the Galapagos islands [PICTURE: BBC]
The aim is to find out more about the spectacular creatures which inhabit these volcanic islands and find out just how vulnerable they are in our rapidly changing world.
Although much of the environment here appears pristine, we know it is not immune to the effects of global warming and one of the mission tasks is to find out more about the impact of El Niño events on the islands.
In her three weeks on board the research vessel Alucia, Liz finds out more about what different scientists are doing to protect endangered species.
And as well as marvelling at the world’s largest gathering of scalloped hammerhead sharks partaking in a “complex mating ritual”, she takes to the water herself in one of the world’s most dangerous dive locations, Darwin’s Arch, hanging on for dear life to the reef as the currents threaten to sweep her away into the Pacific.
From swimming with boisterous sealions to having her mask pecked by a flightless cormorant, Liz is happy to get up close and personal with the local wildlife. Having studied biochemistry and wild animal biology, and with Charles Darwin as one of her “absolute heroes”, it is abundantly clear that this programme represents a dream come true for her.
But as well as serving up plenty of entertaining TV moments, there is also a sense that this mission is actively contributing to science through its ground-breaking findings, something that Liz, who has been appointed an ambassador for the Galapagos Conservation Trust, hopes will be a feature of her work in the future.
“It’s our duty to help communicate what we believe is the most important thing — to understand the wonders of this planet and do everything in our power to protect it,” she says.
Produced by the award-winning independent company Atlantic Productions for BBC Earth in a co-production with Alucia Productions and distributed globally by BBC Worldwide, Galapagos is available for the next three weeks on BBC iPlayer.