Share 'How to know if oranges are ripe?'

I'm considering going on Orange Island, which would be my first island trip!   Anyway I've noticed in a few posts that peeps strongly warn against eating underripe oranges, or oranges that have not been picked ripe.  This will be especially important for me to know since I have major tooth enamel damage already.   So my question is, how do you know if an orange has been picked ripe or not?  And i…