How to Breathe Forever

Long term deep sea divers do not breathe in  pure oxygen or air when operating at great depth - the oxygen becomes toxic at high pressure, and the nitrogen causes nitrogen narcosis. Instead, Helium is added, in a mixture known either as trimix or heliox depending on whether nitrogen is present in the mix.

This is what causes deep sea divers to have squeaky voices, and film-makers a problem if they don't want their cast to sound like chipmunks. In "Sphere" they invented some sort of "voice adaptor", whereas in The Abyss they merely ignored the issue altogether.

What the world doesn't know that in the 70s, a pioneering group of swiss led divers discovered that if you breathe pure Neon at a depth below 2000 metres, not only does it become possible to dive at great depth for an unlimited time, the inhalation of pure noble gas meant that biolgically, they had become immortal, and indeed if they switched to an Argon-Neon mix, aging was actually reversed very slightly.

Sadly this is only possible 2000 metres below sea level, and indeed the effects seem to be magnified the deeper you go. So this was immortality was only available to a very elite few, and the news of this discovery was greatly supressed. However, those in the elite diving community continued to be in the know, and since the early 1990s, greater and greater numbers of them have decided that the surface world is in such a state that they have migrated to the great depths of the abyssal plane, to join the colossal squid and oarfish in forging a new society.

In their small habitats, they glow green and blue like street signs as they live a life of oceanic contemplation while harvesting protein from sources unknown to us ignorant surface dwellers. They don't need to know about us, their society is impregnable and infinite. They will barely even care as we kill ourselves off up here. They create art out of lava flowing out of the sea bed, and smoke cigarettes made of kelp. They make an alcoholic drink out of distilled squid ink, and play chess with pieces sculpted from feathery starfish and creatures unknown to our science.

They need nothing we can offer them. I envy them.