So I Am Buying an iPad, Which One?

[landonshaw]

So I am buying a iPad. Have read on this net that certain models no not need to be in sight of a tower and do not need a WI-Fi connection. So I will be getting the Navionics software and Charts for Caribbean and South America.
My question is: You need the iPad 3 or 4 so that the GPS works out at sea.


On the iPad store website I see iPad 2, two options Wi-Fi with 16g and a iPad 2 Wi-Fi + 3G with 16G


I also see the iPad with Retina display, two models Wi-Fi @ 64G and Wi-Fi + Cellular with 64G


Which is the iPad 3 or 4? and
What is iPad with Retina display?
Thanks, Dave