Newline symbol unicode character

This is how they render on OS X 10.8.5 (Same on FF26/Chrome32/Safari6):

And this is Win7/IE:

Win7+FF looks pretty the same, but Chrome32+Win7 has a problem with U+2936:

8 Years later, this is Win10+Crome91:

There are several possibilities. The choice may depend on font, too, since not all of them are available in all fonts, and some of them have rather varying shapes, and some work better in small sizes than others:

⤶ U+2936 ARROW POINTING DOWNWARDS THEN CURVING LEFTWARDS
↵ U+21B5 DOWNWARDS ARROW WITH CORNER LEFTWARDS
⏎ U+23CE RETURN SYMBOL
↲ U+21B2 DOWNWARDS ARROW WITH TIP LEFTWARDS
↩ U+21A9 LEFTWARDS ARROW WITH HOOK

To represent an abstract idea of new line, rather than a symbol reflecting a keyboard key for new line, you could consider these, too:
␍ U+240D SYMBOL FOR CARRIAGE RETURN
␤ U+2424 SYMBOL FOR NEWLINE

What about right-to-left languages? Let's test it!

<div dir="rtl" style="white-space: pre">
مثال ⤶ U+2936 ARROW POINTING DOWNWARDS THEN CURVING LEFTWARDS
مثال ↵ U+21B5 DOWNWARDS ARROW WITH CORNER LEFTWARDS
مثال ⏎ U+23CE RETURN SYMBOL
مثال ↲ U+21B2 DOWNWARDS ARROW WITH TIP LEFTWARDS
مثال ↩ U+21A9 LEFTWARDS ARROW WITH HOOK
مثال ␍ U+240D SYMBOL FOR CARRIAGE RETURN
مثال ␤ U+2424 SYMBOL FOR NEWLINE
</div>

In my browser, it renders like this:

As you can see, the arrows stay pointing in the same direction, even when right-to-left mode has been set. This may or may not be what you want.