Activate the following cheats by entering the corresponding codes while holding ENTER:

CHEAT FUNCTION - KEY
See through land - 1
Show park boundaries - 2
See through all rides and attractions - 3
See through trees - 4
Remove supports on all rides - 5
People disappear - 6
Grid lines on land - 7
Mark land with height markers - 8
Mark rides with height markers - 9
Mark paths with height markers - 0
Black grass - H
Black dirt - V