Being that bottom contours and 3d bottom views aren't of as much use in the marsh I got the inland southeast region card of platinum plus. Of course there are other platinum plus features that I don't use as much that could be of value in the marsh.
The base map works for me in the marsh. The inland card I have covers all of the southeast US. From Texas to the Atlantic coast, and from LA and Florida up to Tennessee.

Does the coastal version allow you to overlay the Google satellite map over the basemap like the inland version? (on the inland version there is no google map overlay option for the coastal areas)