HB units can use Navionics and LakeMaster mapping cards ...
Your 598 uses micro SD Card size so as long as you buy new - you will get a micro SD Card in an SD Card adapter ...
Check coverage in Navionics for your lakes here ...
https://webapp.navionics.com/#boating@6&key=slg~Et~ezO
And here is the LakeMaster regional cards ...
http://www.humminbird.com/Category/Support/Find-a-Lake/
Rickie