I've done some research online to find out how an AOW diver can become a PADI divemaster, and all I found everywhere was that you need the rescue diver course (plus the divemaster course). I went to a local dive shop, and the guy told me that I'd need 5 specialities as well. Is that true?

I am currently a Dive Master candidate in the PADI certification system. Although it is highly recommended that Dive Masters gain as much experience as possible, it is NOT required that you have 5 specialties. Is it possible that this guy is more interested in making a buck than helping you achieve what YOU want?

I believe he was confusing the master scuba diver. Master scuba diver certification is five specialty areas.

True

Try checking the PADI website for current requirements. www.padi.com

What is needed to be a DW is as follows.

Rescue Diver
20 dives to start the program
Complete the DM course + all tests
60 dives to finish the Cert.

There are no specialties need to become a DM.

Hope this helps.