Multiple Cool heightmaps you will have to do the file sizing yourself, tutorial https://www.youtube.com/watch?v=sIhbyLSnvgw
1. Create a map on Unturned with the workshop editor, name the map and choose the size.
2. unzip the Height Map you just downloaded.
3. Go to C: Drive / Programe Files / Steam / SteamApps / Common / Unturned / Maps open up the map name you just made.
4. Size the map the way you saw in the tutorial.
5. Put the image into your Maps Terrain folder you just created.
6. Start Unturned and edit your map