Blue Planet 2
The BBC program features footage from beneath the world's oceans BBC

At its peak Blue Planet II has brought in audiences of 10.3 million, according to BBC stats.

The BBC1 wildlife series, which is screening 16 years after the original, was made over four years and features 125 expeditions in 39 countries. It's a visual masterpiece that has captivated much of the country.

That isn't the case for everyone, however. In fact, a number of people don't just dislike Blue Planet II, they're terrified of it. Christopher Jones is a leading expert in phobias and is referred to 'the breakthrough expert' on his website. He spoke to IBTimes UK and says thalassophobia "is basically a fear of water and specifically thoughts of oceans."

As for being afraid of the sea – and under water specifically – it's hardly a recent fear that's been exacerbated by Blue Planet II. Big cultural moments such as the popularity of Jaws led to widespread fear and misinformed prejudices against sharks and the sea for decades, for example.

He says that "like many other phobias it's often triggered from negative experiences in childhood". They form a "complex specific phobia that either starts from bad experience of water when you were little and nearly drowned" or something wider such as "a form of agoraphobia that makes you feel inferior when looking out to sea".

With the former he says "this triggers a survival response that is a subconscious response designed to keep us alive. Now whenever you see that thing in future, or think about that thing, the same survival response" will kick in.

It's estimated that in the UK up to ten million people suffer with phobias. Whilst thalassophobia isn't one of the most common ones according to Jones – it wouldn't make the top ten – he says it often appears as a symptom of other fears.

In a fear of flying for example, this could stem from claustrophobia, fear of heights, fear of crashing or fear of being out of control. He even says once he investigated this fear further in a patient and uncovered that it was flying over oceans and water that caused their panic.

Jones cites Pavlov's dogs when explaining more about this. In the early twentieth century, Russian psychologist Ivan Pavlov highlighted that his dogs' behaviour (i.e. them salivating) was a response to an association they had formed (i.e. him coming into the room with a bowl). The dogs weren't born doing this so it must have been a learned behaviour in response to life experiences.

"With human beings it happens in exactly the same way; we hear a piece of music and we're kissing the love of our life, ten years later we can hear that tune and we're back there hearing those positive feelings. Similarly, if a tune that was popular when the love of our life was breaking up with us plays now, we're back there to those emotions."

"We link like this all the time and that's essentially what happens with this phobia – you become hardwired to it in your past and whenever you experience it again, it's firing off these fear responses."

He says that in the past our primitive brain would learn to associate real threats such as a tiger with danger as a form of self-preservation. Our natural responses in a state of danger are to go into "fight, flight or freeze – if you're trying to get away from it and it gets angry you could fight it, you try and escape it or you play dead – so you freeze."

Can you ever be cured from a phobia?

Jones says people can definitely be cured.

"Nearly all fears are learnt, there's a couple that aren't but most are, so if we can learn to be scared, we can learn to be happy."

While exposure therapy – a method in which patients confront their fears instead of avoiding it – is thought to be the best long-term method of combating anxiety related disorders, Jones firmly disagrees.

"I don't recommend what you call exposure therapy as I find it dated and painful... I find people are worse for it. It's not necessary."

Instead Jones thinks that people need to consider their phobia more.

"What I recommend is dealing with the root cause, working on those internal behaviours, thinking about what we're picturing, what we believe, how we hold ourselves, how we breathe and how we change those patterns. So whatever the trigger is in your past go back and work on that emotional response and take away the emotional charges – what we call memory re-consolidation."

He says: "Logically we know it's not realistic but emotions aren't logical. Today we're taught to tackle everything with logic but... these are irrational phobias, the clue is in the title."

If we want to really understand them, we have to "go into the depths" of what we feel. Only then can we really stop it.