edmarriott, while there are no subsims originally designed for Mac OS (as far as I know) there are several programs that facilitate running certain games on Mac OS and other platforms such as Linux.
One important program to try is an emulator called
DOSBox. If you could get it running on your Mac then you will have a large selection of old subsims to choose from. Head over to their main website and check out their FAQ and Wiki for more information:
http://www.dosbox.com/
If you are feeling particularly bold you may even try the "Windows compatibility layer" known as
Wine. I use this program in Linux to play Sub Command and Dangerous Waters and it works very nicely so long as you take the time to configure everything properly. More info on this at their website and Wiki:
http://www.winehq.org/
I have no experience with Mac OS, so I cannot tell you with any certainty if any of this
will work for you, but it is certainly a
possibility that they will.
If you can sort through the platform-specific issues and get either of these two programs to run under Mac OS then others and myself will happily guide you through the rest of the process. Feel free to ask any further questions in this thread.
Welcome to the forums.