Ahhh now here is the issue..
What people don't realize is the charts
uses for the USA are made and supplied free of charge by the US Coast Guard. These charts
are completly free and most of the "For profit" charts use these as a basis for thier USA charts.
There are a bunch of other countries that provide charts free (except us cheap
Canadians). You can get some links here.
Chart Sources | Official OpenCPN Homepage
For other charts, you will need to purchase
them and it can be complex. Here is the link where you can buy the User Permit
to enable chart purchase
Now.. You might hear about CM93 charts that people use (worldwide). Most of the people obtained these charts through illegal means as they (the chart company) were hacked years ago. So these illegal charts are available on the internet
if you look for them.