underwater maping software

[bhampton]

I am a scuba diver and I am looking at making maps of specific areas where i dive by getting a fishfinder/gps and logging the XYZ data to a laptop and doing a grin with my boat.
the deps are shallow 0-150feet or so. I was wondering if anyone had any imput on what software would be good for this poormans cartography?
I am leaning tword one of garmins units which I have the most experiance.

[dbo]

Are you talking about underwater cartography or mapping the area above water?   GPS satellite signals won't penetrate more than a few feet of water (if you're lucky).  I did find this: http://www.wadespage.com/D800DS07RF00.shtml maybe it will help.