TrueCrypt alternative for Mac OS X

I'd need to create an encrypted volume on my MacBook Pro running OS X El Capitan. It's been a while since I needed to do something like that, I think it was 2010 when I used TrueCrypt. I know that nowadays its development has been suspended or somehow discontinued, so I was wondering: how to have an encrypted volume with TrueCrypt-like level of security on Mac OS X?