Passport?

I'll be in Puerto Rico next month,can I hop the ferry to DR with only a picture ID?

I've heard of some people who are able to get in with just a copy of their birth certificate. HOWEVER, they either had to plead or pay up. Some have been denied entrance. So my advice to you would be to take the safe route - TAKE THE PASSPORT!!!

I don't know about now, with all of the increased security and such. I haven't been there since August, but then it was still fine to come with only two forms of identification (one being an official-issue birth certificate)

Why do people like to complicate their life ? Just have a passport done if you don't have one. You will be happy you have it. Don't take any chances and stop asking you need your passport to go somewhere. Just take it!