The mesmerising and mind-bending sci-fi show has reached its conclusion after three seasons, and it's likely fans will have a lot of questions following what was an epic final episode. We've done our best to answer as many of those questions as possible here...
Dark season 3 ending explained
The finale starts with Claudia approaching Adam - something which Adam finds deeply confusing, given that in every previous version of the loop this has never happened. Claudia explains to Adam that his frequent attempts destroy the knot have only ever kept it in tact, including the act of killing Martha and her unborn child.
Claudia further explains that both Adam's world (the one in which we have spent most of the show's three-season run) and Eva's world (which was introduced in season three) should both actually never have existed, they are offshoots that were created when HG Tannhaus' experiment went wrong in a third world - the origin world. (For the rest of this article I will refer to the three world's as Adam's world, Eva's world, and the origin world).
Claudia has spent 33 years across Eva's and Adam's worlds trying to stop the loop from repeating (thus saving her daughter Regina from dying of cancer) but realises that it is impossible - everything that happens in both worlds is bound to keep repeating, perhaps not at the same time or in the same way, but no one in either world can escape their fate.
Using a loophole - that during the apocalypse, time stands still and it is therefore briefly possible to change the chain of cause and effect - Claudia is able to approach Adam to explain all this, and tells him that he must now send his younger self, Jonas and the version of Martha from Eva's world to the origin world in order to stop the event that results in the formation of both worlds - in essence wiping them out of existence.
Adam goes to Jonas - at the time just after the Martha from his world has been shot - and explains to him that the only way he can prevent himself turning into Adam is to go ahead with this plan. Jonas then fetches the Martha from Eva's world - just before she is grabbed by Magnus and Franziska and the loop is repeated again.
Jonas is successful and along with Eva's world Martha he travels to June 21st 1986, the day on which the passage was opened for the first time, and Adam and Eva's worlds were created. HG Tannhaus' had been attempting to go back in time to prevent the car crash which kills his family but instead he accidentally splits time, creating the other worlds. Jonas explains that for a brief moment, when the passage is created, there will be a bridge between all three worlds - at which point he and Martha will travel back to the day of the fatal car crash in the origin world to prevent it from ever happening.
And so Jonas and Martha separately walk through the bridge, a kind of starry void in which they briefly see childhood versions of each other, before finding each other and stepping into the origin world. They then successfully stop the crash by standing in front of the car, forcing it to stop, and telling Tannhaus' son that the bridge ahead is closed and that they will have to go home - an instruction he begrudgingly accepts. And so, the car turns back, they stay the night back at HG Tannhaus' and the crash never happens, stopping Tannhaus from using the time machine and preventing Adam's and Eva's worlds from ever being created.
Do Martha and Jonas die?
Well, not technically - what actually happens is that they are wiped from existence entirely, since they never existed in the origin world, so they can't really die in the traditional sense. But they do stop existing.
In some of their final moments, Martha and Jonas confide in each other that they saw the childhood versions of each other in the bridge - and speculate about what this could mean. Martha asks "do you think anything of us could remain, or is that what we are - a dream? We never really existed." Jonas responds that he doesn't know, but proclaims that "we're a perfect match" and the pair hold hands (we soon see Adam and Eva doing the same) as they slowly disappear from existence while a slowly sung version of 'What a Wonderful World' begins playing in the background. How romantic!
What does Dark's final scene mean?
In the final scene, in the present day in the origin world, (now the only world) we see a pleasant-looking dinner party with guests including Regina Tidemann (who has not died from cancer), Peter Doppler (who now appears to be happily living with the transgender woman with whom he had been having an affair in Adam's world) and a pregnant Hannah Kahnwald (although she obviously doesn't have this surname as Mikkel Kahnwald doesn't exist anymore). There are a number of absentees, including Ulrich Nielsen and Charlotte Doppler, given that they no longer exist, since they relied on time travel to be born in the first place.
And while it is clear that the other worlds no longer exist, they also seem to have some kind of hidden lasting impact on the characters in the origin world - with Hannah seen staring in shock at a yellow coat (identical to the one worn by her son Jonas in Adam's world) after the joking mention of an apocalypse. With some of her final words of the series she says "I just had deja vu or something. This might sound absurd, but this is exactly what I dreamt last night" - and it seems she was somehow aware, in some sense, of the other worlds ending. Then, with her very last line, she declares, when asked about a name for her unborn child, "I think Jonas is a beautiful name."
So it seems that while the other worlds might have been wiped from existence, they still, in some sense, exist in the subconscious of the origin world's characters.
What is the origin?
For much of the series, there was talk of an 'origin' that, if destroyed, could get rid of the knot and stop the loop. Adam is convinced that this origin is the child of Adam's world Jonas and Eva's world Martha, which he thinks ties the world together (we see that child at various stages of its life, child, young man and old man, often travelling together).
But it turns out this was another red herring - Adam's attempted destruction of Martha's unborn child was just another thing which perpetuated the loop. The real origin, as mentioned above, was the car crash which caused origin world HG Tannhaus to create and use the time machine in the first place.
Who are Eva and Adam?
Eva and Adam are grown up versions of Martha and Jonas in each respective world - and are the key to ensuring the loop keeps repeating, even though at different points they are both trying to stop it.
Jonas explains to Martha, "We're the reason everything happens the way it does. Why it happens again and again," and later Adam to Eva "We are responsible for this never-ending Deja Vu." This is why it ultimately falls to younger Jonas and Martha to go to the origin world and stop the crash that put all the events in motion.
Some viewers will undoubtedly have further questions, and no one will have all the answers - as the show itself repeatedly says, "what we know is a drop, what we don't know is an ocean" but all in all the final episode wrapped up Dark in a very satisfying - albeit occasionally confusing - manner.