Scuba diving is AMAZING! I did my cert while I was on holidays in Bali, but you should be able to do it pretty much anywhere. PADI is who I got my cert through and they are internationally recognised. There's another company that is also internationally recognised but I'm not sure who they are. I'd reccomend going with a dive school that uses either of these so you can then dive anywhere in the world. With PADI, I was able to do all the theory online which saved me having to sit in a classroom while I was on holidays. The cost of doing your cert should cover everything you need equipment wise. My course cost around $1000 from memory, but will cost a bit more doing it here in Oz. I spent 2 days doing my cert - mornings were spent doing my confined water dives (some places do this in a pool, I did mine in the shallow water at the beach) and then the afternoon doing my open water dives. I really wish we'd done it earlier in the holiday so we could have spent another day or 2 diving. Once you have your open water cert, you can then do a photography course. Not sure what the cost is if you're using their equipment, but I know purchasing your own equipment (decent camera and underwater case) is very pricey.

As far as finding somewhere to do it, I'd recommend looking for reviews on trip advisor. That's how we found the dive shop I did my cert through and they were just as fantastic as the reviews said.

Diving really is so amazing. I could easily spend all day under the water, it's just so peaceful and the sealife is amazing to watch.