When I use to play Super Mario I got very good at it.
They claim they understand this game perfectly & yet… they still do not.
I have yet to see anyone realize this so i doubt very much they do still.
I got so good. “not lost worlds” thee original Super Mario Bros!
I beat the game multiple times with… one life.
After you beat it once, enemies change.
I beat it eight times in row in one play. one time normal then 7 with enemies changed
So I decided to start trying all the glitches I found in the game & any other strangeness. ohhh what about the -1 world
Well after beating the world once, i realized you could use Beetle Baileys* in the first level before the final steps to stomp one & get free lives.
much hard to do with a turtle & harder to catch him on the stairs on 1-1, or on… 1-2, but… you will need them for minus one. “for accidental deaths & the water pit starting issue”
So I took those free lives & dipped into -1 “the negative world”
it is a mirror of 7-2, they look the same but sadly -1 is unending correct?
maybe not! video how to get to it.
They say to this day it is unbeatable, this may in fact be true, but one thing they seem to have not realized is if you play the stage like you are playing 7-4 but in like 7-2 “the -1 water world like a maze you continue to get closer to the end, you can not swim the easiest paths.”
hmmm, 7-2 is a just a glitched minus 1 world, just maybe… 7-4 is part of the answer then & they are two worlds… glitched into one world?
The problem I ran into is I was only able to find this pattern & a solution “for possibly beating it” just before i lost my ability to play it again. i lost the chance to fully test my theory to completion
“but I was so damn close to beating it if correctly if possible & maybe a negative two if I did.”
but the last time I went through that pipe, I appeared at the end & had to choose which path, I had so little time left… I could not choose if it was all top, all middle, all bottom or any variation in between them.
*yes I know they are now called Buzzy Beetles.
https://gamefaqs.gamespot.com/nes/525243-super-mario-bros/map/9652-world-1-map
use above link to follow the places you will appear if you take the right paths
level start duh. under the second group of coins, third somewhere after the third coins but before the fourth set, it gets hazy, but you will eventually start in the water pit! You best be beating the heck out of swim long before you start to appear. last place you should appear is after the six coin pit but before the four black maze. the first path i took was incorrect & i ran out of time & never played it again.
there is more then seven paths on the last four block, sometimes you have to back track on 7-4 to move forward, could be a solution also. 
~QS