I just found this site:
It enables you to view Navionics marine
maps worldwide for free. You need an internet
connection, but the maps seem identical to conventional Navionics
offerings with nothing to pay. You do not need to download anything at least on my tablet. Just click the webpage and you can instantly scroll anywhere and view Navionics marine
maps with full detail.
I hope there are no copywrite violations. It seems to be a service
offered directly by Navionics.
Great for background research
of new areas.
As an example, this is a typical sceenshot.