nginx: redirect root to subdirectory while maintaining url

I have an nginx setup with folder structure like this:

- www
|- splash
|- blog

www is the root folder.

I would like to redirect users who access http://mysite.com to the splash folder.

But I don't want the URL in the address bar to change to http://mysite.com/splash.

The URL in the address bar should still be http://mysite.com.

This rule should only apply when user accesses the root folder.

Meanwhile accessing the blog folder will be as usual via: http://mysite.com/blog.

How do I achieve this? So far my conf is as follow: (they don't work btw)

location / {
    root /www;
    index index.html;
}

location = / {
    root /www/splash;
    index index.html;
}

Cheers!