The second instalment of the BBCs long-awaited Blue Planet II series, The Deep, is a true spectacle, of course it is, it was always going to be. It is a beautiful work of art, visually stunning, and also of course very entertaining which ultimately is what is was made for. The advances made in underwater lowlight filming made the bioluminescence all the more spectacular, and one would have to be numb to not find themselves in awe when watching six-gilled sharks feast on a dead whale carcass. It was also great to see Osedax getting a mention, although admittedly under their pseudonym ‘zombie worms’. The true value of this episode is simply bringing these organisms to life, in particular the myctophids and the cock-eyed squid amongst others.  Watching the Synaphobranchid convulsing with toxic shock having found itself too close to the brine pool was fascinating, and marvelling at the small crustacean ‘born’ into a sponge prison was an incredible piece of filmmaking. Although deep-sea biology has progressed massively, even since Blue Planet I, it is still notoriously difficult to really capture the essence of a lot of these animals alive and it takes a landmark documentary like this to make that happen.

The geological aspect of the episode was also very impressive.  High Definition footage of the methane escaping from the seafloor to the unrestrained violence of underwater volcanism is always fascinating, and then tied together with the hydrothermal vents and their endemic fauna is a necessary must in a film like this. It was also fantastic to see the hadal zone (depths exceeding 6000m) included alongside the usual mainstream deep-sea topics. I took special pleasure in reminiscing about the time I was sitting somewhere over the Mariana Trench in 2014 and the technician behind me was watching back some footage from that mornings lander deployment and tapped me on the shoulder and said “Hey Al, what’s that?” to which I replied “that my friend is now officially the deepest fish ever seen alive” (until we filmed it even deeper two days later). And here it is on the Blue Planet. It was also great to hear Attenborough utter the name ‘Ethereal snailfish’ in a landmark documentary as it is a nickname coined by my colleagues after much discussion in the days following the discovery.

The Hadal Snailfish going about their daily business at 7200 metres deep.

Speaking of that lander –the ‘hadal-Lander’ – it also got featured in this episode, or a least a full-size replica of it was seen descending into the Mariana Trench. There is a great deal of personal satisfaction seeing something I designed and built myself that I have used so much in recent years being featured in this type of film. The real one, however, now resides broken and sore in a hangar at Wallsend in Newcastle after being trashed by a Hokusai inspired ‘Great Wave off Kanagawa’ earlier this year on its way back to Tokyo from the deepest place in the world. At least it's spirit lives on in the Blue Planet II.

Here’s a revelation though: Although it may sound strange coming from a deep-sea biologist I have to admit that I have an unspoken policy of not watching nature documentaries on anything relating to the deep sea. This is not because I am overly cynical but rather I get frustrated at how the media have a relentless propensity to ‘enigmatize’ the deep sea. All too often as soon as something has ‘the deep’ in the title, the usual deep-sea suspects are rolled out to spooky music and introduced one by one like a travelling Victorian freak show. The insistence of making deep-sea organisms ‘mysterious aliens/creatures/monsters of the deep’, to me at least, puts a chasm between everyday people and the largest marine environment on earth, which in turn distances us from an intimacy and the duty of care that it deserves. However, this is the BBC’s Blue Planet II, I have to watch it because I have contributed to it and clearly I have been asked to write a review of it.

Given what I have just said about how the deep sea is typically portrayed, I can’t help but mention the first 10 minutes.  The deep-sea organisms are twice referred to as ‘Alien’, and ‘strange creatures’, and the depths beyond sunlight (which is most of the planet) is referred to as ‘eternal gloom’ and the ‘midnight zone’ the latter of which I have only ever heard used in the kids marine-themed cartoon ‘Octonauts’, but maybe I am wrong. But for me there was one statement that I cannot pass over likely: “we know more about the surface of Mars than we know about the deep sea”. This utterly ridiculous statement used to be the moon and it will simply not go away. You would not believe how many times we hear this in our business. So, as soon as the episode was finished, I decided to go and look this up.  The earliest mention of this statement I could find (when it was still the moon) came from George E.R. Deacon who, in the Journal of Navigation, quoted Sir Edward Bullard (who died 37 years ago) as saying it.  This paper was published 64 years ago in 1953, 15 years before the moon landings. The upgrade from the Moon to Mars, as benchmarks to how much we know about the deep sea, appears to have been used in various disciplines, but in the deep-sea context maybe happened around 2010. Does this mean we now know more about Mars than we did about the moon in 1953? Does this mean we still know more about an icy lifeless spherical rock drifting in a vacuum in 1953 than the vast oceans of our planet that hosts millions of species over hundreds of habitats with an inconceivable number of interactions? I personally think we actually know a lot about the deep sea.  Not everything, but a lot, and the Moon and Mars are an unfair comparison. Someone needs to end the use of this statement.

A Trachymedusa drifting over the abyssal plains of the NE Atlantic at 4800 meres deep 

The thing that I like about a series like this is its great legacy and phenomenal reach.  I know from teaching at University that documentaries like this are very important at inspiring new interest in the topic, and a solid marine biology documentary is long overdue.  The Blue Planet II, if it is anything like the Blue Planet I, will serve as a blue print for what a generation will think of when they think about aspects of the oceans, and what we had tonight is the new blueprint to what a generation will subconsciously accept at what the deep sea is like. The deep sea and the deep-sea community is awe inspiring in its own right, but I can’t help getting frustrated when I see that the makers can’t help but unnecessarily finish it off with more crazy sensationalist statements about how many jumbo jets stacked on top of each other equals the hydrostatic pressure or if hydrothermal vents was where life began (a very contentious subject) and the usual formulaic statement about analogies for life on Jupiter’s moon Europa, but the then fail to mention Europa’s Oceans lie under 3.2km of ice, are 96km deep, and temperatures rage from -160 to -220˚C. 

The deep sea is an amazing and awe inspiring place and this episode did largely convey that well, but the urge to over enigmatize and sensationalize, for a slightly cynical deep-sea biologist at least, is a constant detraction from the deep-sea reality that is already sensational and often enigmatic in its own right.

This is what landing in the deepest place in the world looks like: 10,890 metres deep.