Question: In [Triangle](http://www.imdb.com/title/tt1187064/), at the start when Jess arrives at the boat for the "first" time, is this the start of the continuation of the ending scene?

It's known that the cruise ship and any surroundings after leaving it is in a time loop.

Though Jess remembers the ship and tells Greg, she makes no indication that she is in the time loop. So yes, the movie was meant to confuse the user. But seeing that, according to the number of dead Sallys on board, the time loop occurs more than 20 times.

So, the first time she entered the loop, the storm sent her into an alternate reality with the never-ending time loop? Is this what the movie was showing? I noticed there is a deadly Jess that was not really in the foreground that got shot in the head, and stabs Sally and Downey in one of the rooms. I cannot really place where she falls into the picture seeing that one of the previous Jess instances killed that Jess instead of letting her jump overboard.

So is there a separate timeline/reality?

Answer: 
The movie *just* shows us the never-ending loop in which Jess is stuck seemingly forever. What *actually happened* that left her in this loop is never shown. Only subtle hints are given throughout the movie.

There is no starting point to the loop. That just seems so to the viewer. I would say that the instant she has the car crash with her son was the starting point. In fact, it's possible that she was an abusive mother who actually killed her son in a mad fit of rage. When she arrives to the dock for the first time, she says that her son is at 'School' as she is unable to come to terms with what she has done. The whole movie revolves around the 'never ending hell' she goes through because of her guilt. She keeps thinking that she can do something to 'save' her son. I believe that the cab driver also has a role to play. There was something suggestive in the way he says stuff like

> 
> I'm just a taxi driver.
> 
> 
> 

and 

> 
> So, I will keep the meter running? You promise you will come back,
>  right?
> 
> 
> 

Maybe he 'represents' the devil, waiting for her to accept the truth and be free from the loop of constant suffering?

She kills the 'original evil mom Jess'. This also represents her inability to accept the truth. She later tells her son how things will be better from now on.

Another point to take into consideration is the fact that initially it seems as if the time loop is restricted to the Ship. But the scene where she discovers the dead birds in the pit, shows that she realizes that it's her whole life, for that particular day,and not just the Ship. She can't just run away from it.

Time on Jess's watch exactly matches the time on the Ship. This is not the case for anyone else. Another indication that the whole time loop is just about her.

The Jess that stabs Sally and Downey can definitely exist. The events will happen as they 'should' unless Jess does something different. Everyone else will act the same way. The scene where she confronts 'the new Jess' with the gun but is unable to shoot, this new Jess runs away and is shown *killing* the 'Masked Jess'. The movie never shows what happens to her. Maybe she is the one who ends up stabbing Sally and Downey.

So, to summarize my answer, in my opinion,the movie starts out with an impression of being a strange sci-fi/time-loop movie (which it kind of is), but the part where she returns to shore and thereafter indicates something more which is going on, apart from the time loop on the Ship. That's my view. 

PS: Check out the story of [Sisyphus](http://en.wikipedia.org/wiki/Sisyphus).
What I think is that the "good Jess" is the only surviving Jess, at both the beginning, the "exactly the same" Jess mentioned that her kid was in school, which means, her son died. Therefore, at the first part of the movie (before the storm), there are actually two Jesses, one who was killed, and the one who killed. Therefore, the one who go on board at both the beginning and end was actually the same Jess. And no matter what, Jess from the other dimension goes onto the large ship died because of the "good Jess" (you can consider as the prime evil). But it also seems like, when the loop of the "good Jess" repeated, she lost some part of the memory, what I think the moment she lost the memory was after the dream on the boat Triangle.