I'm only curious, I don't want to fix this.
I asked a friend to make a level (shitty) but he made something strange: he made possible to swim in lava in that level.
He doesn't know how he done this.

To go to the strange lava you must:
1. Find a way to bypass the bounce balls and get into the tube.
2.You will get in another zone. There is the lava, and you can swim into.

That's the link to download the level:
https://mega.co.nz/#!FtgikISQ!B5ZCgVcq72fATnJFS5cbJ7pYEwIptnF05cOeOZnYcD4

Lava sprite settings:
ID 1: 0
ID 2: 0
Unknown 6: 1
Unknown 7: 15
Tile to rise: 0
Speed to rise: 0
Raw sprite data: 00 00 00 1F 00 00

Do you know how he did it?

You can swim in lava if you warp to the same area in the level.

You can bypass this, but its annoying.
I had this problem in my hack.
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At the risk of sounding like a broken record, someone forgot about his very own thread : http://nsmbhd.net/thread/2141-water-or-lava/

But as  gridatttack said, you can fix this; for example by placing invisible tiles that emulate "death by lava" behavior on the surface of said lava.

That is so cool! Im going to use this
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rush b сука блять