[c#] newline character in c# string

I have some html code in a C# string. If I look with the Text Visualizer of Visual Studio I can see it has numerous newlines in it. However, after i apply this code

string modifiedString = originalString.Replace(Environment.NewLine, "<br />");

and then I look with the Text Visualizer at modifiedString I can see it doesn't have anymore newlines except for 3 places. Are there any other character types than resemble newline and I am missing?

A great way of handling this is with regular expressions.

string modifiedString = Regex.Replace(originalString, @"(\r\n)|\n|\r", "<br/>");

This will replace any of the 3 legal types of newline with the html tag.