Some kind soul created this useful map showing the lines on the island:
Post closure development has erased a lot of the line's alignment. A major road development at Newport has removed all signs of the railway station, and the the route to Cowes is almost untraceable on Google Maps.
Other parts are still visible, often as walks and parts of the Sandown - Newport -Cowes line makes up part of National Cycle Route 23.
So what might have been in a more Railway friendly universe?
To be continued...
References:Map from Wikipedia commons
Wikipedia article on present Island Line
Hardy, Brian (2003). Tube Trains on the Isle of Wight. Harrow Weald, Middlesex: Capital Transport. ISBN 185414 276 3.