How to turn off iphone cellular data?

I'm going on a cruise today and I don't want to receive texts or calls or I will be charged! How can I temporarily turn off my service? I still want to use my phone for music and Wi-Fi if possible!

Put it on Airplane mode, it's easier, its in settings and then there's a sliding tab for it

As the other said, just tap on the airplane mode. That means no calls or texting but Wi-Fi and everything else works, I think you can actually still use imessage even in airplane mode and its always free even from other countries, etc. I used my iphone on a cruise this way.