Interior Panelling

[froggy]

My bay is a converted van, and to be honest the interior is looking a bit tired.
It is panelled upto just below the windows.
What is the best stuff to use to replace this panelling?

Not the best of pictures but hopefully you can just make out what im talking about.

 

[froggy]

Anyone got any ideas?
Plywood?
Hardboard?

 

[Araon]

Marine ply, if damp or condensation get in then the panel will not/should not blow as easily....

or go for the bog standard MDF precut panels and seal them and put what ever covering your wanting over the top