Last night's episode of Blue Planet II took us to the coral reefs of the world, showing us many of the creatures that live there.
Despite the beauty of the reefs, the episode brought a lot of viewers down as it was made clear just how much human activity has damaged them.
Viewers took to Twitter to discuss just how desperately we need to take care of the planet:
And of course, people love David Attenborough just as much as ever - with some calling for him to rule the world:
Another talking point on the episode was the terrifying Bobbit, a predatory sea worm that snatches fish from the sea floor:
But the BBC team managed to bring some light to the horror of the polluted oceans:
Blue Planet II continues next Sunday at 8pm on BBC One with an episode on the Big Blue.
