Ya thats what I thought. I did a little checking cause I also wanted to go diving on a reef on my honeymoon. Certification takes 3-4 days depending on how fast you learn it.
I would highly recommend you find a very reputable shop that will take more time than just 3 to 4 days with you. The more time in the pool and in training, the better time you'll have diving. I was fortunate to take the class at MTSU, so I had 15 weeks (for open water... I did more training at MTSU after that) and wouldn't trade it for anything. Chris (fishdoc) also did his certs at MTSU. This is something that can very quickly become life and death and you need the skills to protect yourself and your dive buddy. Its well worth investing some time into.
Brandon