I understand, this ought to be easy, however i cannot have great results.

I've 2 domain names pointing towards the same folder within an Apache server, bahiadivers.com and bahiadivers.cl.

I wish to redirect bahiadivers.cl to bahiadivers.cl/es/ and alter the address bar.

I attempt this (among millions of things)

rewritecond %{HTTP_HOST} ^bahiadivers.cl [nc]
rewriterule ^/$ http://www.bahiadivers.cl/es/$1 [r=301,nc] 

but did not work... I am talking about, the URL isn't altering within the browser address bar, but the languge (/es/) isn't working... how must i do that? Thanks!

Do this for the .htaccess

# Apache configuration file
DirectoryIndex index.php

<IfModule mod_rewrite.c>
   RewriteEngine on

   # If URL is www.example.com/es/Blah, use /Blah/
   # Prevents needing to change existing links.
   RewriteBase /es/

   # Rewrite www.example.com to example.com
   RewriteCond %{HTTP_HOST} ^www.bahiadivers.cl
   RewriteCond %{HTTP_HOST} ^bahiadivers.cl
   # Rewrite any inbound URL Bits to http://bahiadivers.cl/es/...
   RewriteRule (.*) http://bahiadivers.cl/es/$1 [R=301,L]
</IfModule>

Which should get it done.