This is very, very long, but I address your questions all here: https://www.themoviedb.org/movie/26466-triangle/discuss/58c071f7c3a3684c15000359. Plus a helluva lot (probably too much) more. But I'll also give my thoughts below.

“What I don't understand is that, when an instance dies at home, what iteration takes her place? Might it be that instances that die on the boat and fail to return also fail to kill her, so she goes to the trip, returns home, and starts the trip again?”

A variation of that MUST happen eventually, but during the three crossing loops, we’re actually shown that even when she “dies” and is thrown overboard, she’s revived on the beach (after being dead), thus continuing the loop ad nauseum. We could throw some type of pseudoscientific Bermuda Triangle mumbo jumbo at this, or just straight supernatural elements, or that it’s all a nightmare and isn’t actually happening. I have a matrix of all correlating events that lay out how the loops intersect each other on my OneDrive (link is posted in the URL above). I’ve concluded that this can’t be happening (her driving the harbor) every three loops, however. One sign of this is what’s going on with the keys.

“1) short lived Jess: dies at home and lives only 1 iteration 2) medium lived Jess: dies on the boat, doesn't get back home and lives 2 iterations 3) long lived Jess: survives home, pass by 3 iterations, returns home, kills Jess type 1, gets son killed, returns to the boat and restarts the loop”

You’re close, but I don’t think this quite holds up to scrutiny. Jess Prime (the one who dies at home) never enters the loop (except for the very first time), so she’s not an iteration of the loops (i.e. she’s “pre-loop”). Also, we’re directly shown in the film only two alternating patterns, but three interacting loops. Check out my event matrix spreadsheet for details. A big factor here is the set of keys, which never duplicates, and just keeps getting passed between each Jess iteration one after the other. If Jess Prime were driving to the harbor every three loops the keys would pile up, but they don’t.

The only way I see it working is that every instance of Jess that gets thrown overboard, including the one from the alternate pattern that gets bashed over the head by the boat hook, is revived on the beach. Chris Smith himself indicates in a comment that the more sinister “mean” version of Jess (that alternates with what might be called “nice” Jess) is what she is about to become at the end of the movie, in part because she might remember just a little bit more than “nice” Jess. However, instead of just falling overboard she then gets beat to death with a boat hook, which may hamper any small recollections she had back to square one.

“ “If she takes place of Hess type 1 and reenters the loop, then she'd know everything that will happen, as we see when she gets to the boat and says she does wanna go on the trip. But, if she had lived the whole loop and survived, she'd do things differently. She'd try to survive it again, leave and save her son.”

Unfortunately her memory is effectively wiped, so she doesn’t remember (although we’re given the impression that as time goes on she starts to, even if she never fully recalls everything). Remember when she falls asleep on the boat, has the weird dream of herself dead on the beach, then wakes up when the waves in her dream wash over her feet? Take a look at what she says after she wakes up. In this moment she’s made to forget her previous loop, dooming her to repeat her mistakes.

“One thing that bothered me on the movie is those times when Jess enters next iteration, she knows what her other intance is gonna do, the mistakes she saw herself do, and still do those same mistakes. As when she fights herself and tries to shoot herself and fails again.”

For this, and it is a very good question to raise, it’s her hubris (the core of the message about Sisyphus that’s integral to the story) that gets in the way of common sense. She’s so confident that this time she’s going to succeed that she tries the same things she saw her other version do again (just like Sisyphus did). However, there are actually minor variations. It’s not completely identical if you watch closely. This indicates that the loop pattern is evolving over time.

“I understand she not wanting to talk to her friends because she figured the loop only restarts once they're all dead, but why not talk senses to herself once they had died and the loop restarted? This gets even worse if Jess type 3 is able to reenter the loop when she gets back to the boat. Why doesn't she do things differently?”

This is explained right in the movie, but is easy to miss. She says to herself something to the effect of, “it returns (meaning the capsized boat) when they all die”. Therefore, she thinks that the only way to get the boat to return (so that she can try to board it and escape) is to kill everyone. She becomes so fixated on this that she stops puzzling through things rationally.

“Or is there an instance not shown on the movie, where she repeats all the actions, returns home, kills herself, and this time doesn't leave home and doesn't get her son killed?”

This is not shown in the movie. But if you read my massive post, logically this MUST eventually happen, even if it’s after 60, 80, or 100 or more loops. Because by the very nature of a loop, which has a starting point, there must also be an ending point (which is how there can be a starting point). One can’t exist without the other. So she either must eventually escape the loop (perhaps driving off somewhere with Tommy instead of returning to the harbor), or she just eventually accepts her fate after the crash and moves on into the afterlife. Either way, she chooses to not go to the harbor and continue the loop, which allows what I call Jess Prime to drive to the harbor for the first time and start the whole thing up.

“This comes to 2nd thing I don't understand. If some bodies pile up (Sally at the top of the boat, letters she write telling to kill everybody, bird hit by the car), then they must be created somehow. I accept that her friends have their instanced bodies created offshore, but how are other bodies and stuff created?”

“I mean, her body itself, which is on land.”

Look at it as two environments, one outside the perimeter of the Aeolus (the ship), and one that encompasses the immediate vicinity of the Aeolus, like a time bubble that causes the glitching. The stuff that duplicates was either brought onto the Aeolus from outside it’s “stuck” environment, or is anything she changes like writing on the notes (we could devise some form of entanglement to explain why the stuff she interacts with gets stuck in time). Everything else “resets” when she reappears. There’s one exception to this rule:

“Same goes for the bird.”

The bird is the one problematic element. I’ve devised a theory that the bird comes through the anomalous loop like Jess herself does, turning it into a temporal artifact. I dedicate an entire section on it. However, the movie itself doesn’t directly explain this. Chris Smith just wanted something to allow Jess to become aware that she’s in a loop, but it’s not something movie itself directly addresses. We watch the birds follow her all throughout the movie, however. They’re important to the story, so this is what I came up with. It’s also another case of her interacting with it in a major way (she killed it), but with the exception of the birds nothing else outsidew the Aeolus environment, as I call it, duplicates. However, these ideas may not necessarily work. If the seagull is piling up after looping, why doesn’t Jess’ body do the same? This leads to…

“I guess police just take out the car and hers and her son's body. But if they do, wherever they're taken, they'd pile up there too, right?”

We can only really speculate, but most likely not. But like the seagull, we have to come up with our own theory. Mine is that once a “normal” interaction occurs with her body (the one in the driver’s seat, that is), it loses it’s artifact status by becoming detangling, or by re-entangling with the non-anomalous “real” world. Therefore, the body in the driver’s seat (if there is one) doesn’t duplicate and gets “reset” (which is really just her appearing at a point in time prior to the event, reverting things to a previous state from her temporal perspective). The body in the bag is Jess Prime and so won’t duplicate. It’s also possible that driver-seat-Jess is thrown out of the car and revived like she is on the beach, at which point we see her standing there staring at the wreck. Notice how the sky darkens as the camera pans over to her. This was quite intentional and indicates the possible nature of what we’re observing.

“Maybe she just died on the car crash and the taxi driver was a death god taking her to some other world, and he trapped her on the loop when she tricked him?”

This is very possible. Chris Smith has said the movie is intentionally ambiguous, and that all interpretations are acceptable. It could almost be looked at like a Jacob’s Ladder scenario (although Smith has said he was trying to avoid this notion while writing it), where she fights with her son that morning and slaps him, then they both die in the car crash. What we’re observing is really just her mind trapped in a cycle of guilt for the way she treated her son as she lay dying on the pavement (maybe influenced by a movie or book she recently read about mythology, and while hearing a seagull squawk overhead).

“But that trick was very dumb I must say. IDK the original story, but I'd expect Aeolus to had done something very tricky and well planned to mess with the god. On the movie, he asks her if she needs help, where she wanna go, and let her do whatever she wants. He shouldn't give her all the freedom then be angry and punish her just because she said she was gonna come back pay for the ride.”

There’s more to it than that. I’d recommend reading through my monster-long post for some ideas. These are just my own thoughts, though. I'm not sure there is a right or wrong.

Hello tnx for the reply! I had seen ur post and read parts of it, gj!

during the three crossing loops, we’re actually shown that even when she “dies” and is thrown overboard, she’s revived on the beach (after being dead), thus continuing the loop ad nauseum

Are u sure she died and was revived? I understood she just didn't drown and survived.

You’re close, but I don’t think this quite holds up to scrutiny. Jess Prime (the one who dies at home) never enters the loop (except for the very first time), so she’s not an iteration of the loops (i.e. she’s “pre-loop”). Also, we’re directly shown in the film only two alternating patterns, but three interacting loops. Check out my event matrix spreadsheet for details. A big factor here is the set of keys, which never duplicates, and just keeps getting passed between each Jess iteration one after the other. If Jess Prime were driving to the harbor every three loops the keys would pile up, but they don’t.

That's interesting, I need to watch it again to pay attention to keys being passed.

The only way I see it working is that every instance of Jess that gets thrown overboard, including the one from the alternate pattern that gets bashed over the head by the boat hook, is revived on the beach. Chris Smith himself indicates in a comment that the more sinister “mean” version of Jess (that alternates with what might be called “nice” Jess) is what she is about to become at the end of the movie, in part because she might remember just a little bit more than “nice” Jess. However, instead of just falling overboard she then gets beat to death with a boat hook, which may hamper any small recollections she had back to square one.

If she dies and is revived, that's very gross and would break anything good from the movie.

Unfortunately her memory is effectively wiped, so she doesn’t remember (although we’re given the impression that as time goes on she starts to, even if she never fully recalls everything). Remember when she falls asleep on the boat, has the weird dream of herself dead on the beach, then wakes up when the waves in her dream wash over her feet? Take a look at what she says after she wakes up. In this moment she’s made to forget her previous loop, dooming her to repeat her mistakes.

I think I missed that too. It's very sad if that's happening, maybe it implies that they are/she is indeed dead in hell and doomed to keep repeating it forever, and even she who manages to survive it and get back to land isn't allowed to leave it.

I understand she becoming evil: she lived that odd situation, killed her friends, did her best to survive and live and leave, just to watch her son die. But she forgetting doesn't make sense, I understood that the whole idea of she becoming evil and killing everybody was precisely because that's the only way to restart the loop and she be able to revive her son and do things different so he'd not die.

For this, and it is a very good question to raise, it’s her hubris (the core of the message about Sisyphus that’s integral to the story) that gets in the way of common sense. She’s so confident that this time she’s going to succeed that she tries the same things she saw her other version do again (just like Sisyphus did). However, there are actually minor variations. It’s not completely identical if you watch closely. This indicates that the loop pattern is evolving over time.

Only explanation I see for this is if she does survive the loop and remembers it all, then she's noticing the changes and seeing that eventually she (or some other instance of her) will be able to save her son. So, she's trying her best hoping that this time she'll make it, or at least get closer to, and just don't wanna do something that might break it all. After all, those mistakes don't stop her from going back to land, so they are irrelevant.

I also don't remember which of them are the instance that does returns land, so maybe they are just instances that die on the boat.

All she wants to to repeat the outer loop so she get back to land while her son is alive. I had read ur explanation with 9 loops but I sadly couldn't understand it. As I understand there would have 6 loops: the first 3 when it starts, then 6 more when she goes back to the boat so she resets everything, goes back to land and this time saves her son.

Of course, there needs to be prior loops because the first inner loop starts with her inside, and of course there are the stacked bodies. This shows that the outer loop had happened at least a few times, which implies that somehow she keeps letting her son die and resetting. And the reason for that, what happens that stops her from saving him, isn't clearly shown.

One explanation is her memory about the loop being reset and u said, and indeed I'm now remembering that on the first inner loop she does seem to had forgotten and just have a faded memory of being there before. But this would be the worse explanation possible.

This is explained right in the movie, but is easy to miss. She says to herself something to the effect of, “it returns (meaning the capsized boat) when they all die”. Therefore, she thinks that the only way to get the boat to return (so that she can try to board it and escape) is to kill everyone. She becomes so fixated on this that she stops puzzling through things rationally.

So, it only restarts when she kills everybody, even another instance of herself. That makes sense, else she could just kill everybody else then team up with herself and create a horde of surviving instances, all working together to revive her son. She never helps her other instances, so she does need to (or believes so) kill her instance too.

This is not shown in the movie. But if you read my massive post, logically this MUST eventually happen, even if it’s after 60, 80, or 100 or more loops. Because by the very nature of a loop, which has a starting point, there must also be an ending point (which is how there can be a starting point). One can’t exist without the other. So she either must eventually escape the loop (perhaps driving off somewhere with Tommy instead of returning to the harbor), or she just eventually accepts her fate after the crash and moves on into the afterlife. Either way, she chooses to not go to the harbor and continue the loop, which allows what I call Jess Prime to drive to the harbor for the first time and start the whole thing up

The problem in this is that we don't know what's happening, so we also don't know what's causing it.

If they are in hell or being controlled by some god, then there's no hope and regardless of what she does it will just keep repeating. Specially if her instances that survive eventually lose their memory as u said. In this case, there's no start of end, they just died or got trapped and keep repeating it.

If they're alive and it's something surpernatural on the ocean and land is normal, then it comes back to my question on how the bird is stacking and where land ppl come from.

Maybe the director just wasn't willing to enter on whether she eventually succeeds and leaves the loop, or didn't think about it.

This is very possible. Chris Smith has said the movie is intentionally ambiguous, and that all interpretations are acceptable

Regarding this and the bird and the car and bodies. One thing is a story be ambiguous and let us interpret however whe want what's not explained, another thing is having some elements that don't fit together.

I think it's just a plot hole. Everything would be coherent if she remained on the ocean and never went to land, then we could just consider it was a dream, hell, quantum buble, god power, etc that only happens there and the rest of the world isn't affected. The world moves on and they disappear forever. But director wanted to make an outer loop that circunvents the inner loop, and created this issue of what happens to bodies on the land.

Only thing he shows about this is the bird, which nobody else notices. It doesn't show what happens to the car and the bodies, so we can't know if he'd have some explanation or if he'd turn back on the writing if asked about during that phase. We could pretty much consider that the whole world is reset and ppl just don't notice.

Indeed the only coherency I can see is that they all died and are under control of some god and everything that happens is illusionary. Everything vanishes when she goes back to the boat and the stacked bird is just to mess with her.