Vector background for an app

I need a continous vector background for an app which covers 6 landscape screens tall - so for ipad would be needed at 2048 x 9216 pixels. It is an underwater game and each of the 6 parts of the background would be static on screen at any time so must work in isolation too.
The 6 parts of the continous background - each being 2048 x 1536 are:
1. On top of ocean with pirate boat and small desert island
2. Part of boat visable at top and general underwater feel
3. Underwater with a rock shelf to one side
4. Darker underwater scene
5. Sea bed with sand & plants
6. Under the seabed with a buried treasure.

I would need to use it royalty free for one app which will be sold on multiple platforms.