Slope is the term used for height of the terrain vs water level. Zero (0) slope is water level. -1 is under water. 1 is above water. Terrain manipulation is done by adjusting the corners, or the smallest squares that are at the ends of the tile borders. The nearest corner to you is the corner you are adjusting.

• When on a vehicle, any slope over 20 will cause stamina not to restore. You must move to flatter ground.
• Any slope over 24+ will cause the player to slide down the slope.
• A large cart can drive through water as deep as -12.
• A non-Kingdom wagon (“wagon”; made with a plank as starter item) can drive through water as deep as -7.
• A kingdom wagon (made with a log as starter item) can drive through water as deep as -6 without catching, but at -7 will catch on tiles. Knowing this, it is a good idea to keep slope for underwater roads at -6 or above.
• While in a boat, stamina restores when you stop moving, no matter the slope under the water.