I’ve never been however, here is a photo that someone posted from Puerto Plata.
http://www.divebuddy.com/photo.aspx?PicID=37243&MemID=11833
You can also search for "Puerto Plata" and there is a forum topic that 2 members talked a little about it. Maybe you can email them directly for information or direct questions in case they don’t see this forum topic.
Enjoy your vacation! It sounds amazing!