Click on the Terrain object icon and create a terrain(mountain).
Click on the little E.
Grab the color slider "}" and drag it down. If it doesn't appears, click on the icon to the left of the downward-pointing arrow at the top of the Terrain Canvas window.
Click on the check mark in the lower right corner.
Drag any of the control handles and change the object size.
Click on the little A
Click on the Negative to perform the Boolean operation and set Rotate to 180 on the X-axis.
Click on the ground plane(infinite plane) and select it, and then click on the little A.
Click on the Positive for the ground plane to perform the boolean operation.
Drag and drop the mountain reversed(which transforms into a pond) in the ground plane.
Select the mountain and the ground plane. Since there are no objects placed on them, you may select the All Select from the Edit menu in this case.
Click on the little G and group them.
Click on the little M and set a material.
Click on the small right arrow to the right of the preview window.
Click on the "PLAINS and TERRAINS" category (1), any of the preset materials (2) and the check mark (3).
Click on the check mark in the lower right corner.
The pond is created.
