Getting post content without the navigation

the_content() will output the formatted post to the web browser, if the tag is used in the post it will only display the post up to this point and will out put a “Read More” link.

There are some additional flags in the method to control this behaviour.

See more here.

Alternatively, you may load the output of the content into a variable, if this is what you want to do you can use get_the_content(). This function does not display the content to the screen so you could do further manipulation to it if you wish.

You can read more about the function here.

Typically however the content output would be manipulated using filters / hooks. It is also worth noting that output of get_the_content() is not subject to the same processes as the_content(). It does not auto embed videos etc.