Water

Pick Water in the tool column and its panel opens on the right. The main control is a Level slider. Raise it and water fills every part of the terrain that sits below that height; lower it and the water drains back out. You are not painting a lake, you are setting a height and letting the shape of the ground do the rest.

This is why Sculpt and Water are usually used together. If the shoreline is in the wrong place, the fix is normally to reshape the ground rather than to move the water.

The water moves while you drag, and the new level is kept when you let go. Ctrl+Z puts the old one back. While Water is in your hand, the map shades what the water covers.

When the water in your world offers more than one look, the panel shows them as tiles under Look so you can choose between them.

The Advanced disclosure is built from the water’s own controls rather than from a fixed list we wrote. What you see there is whatever your world’s water actually exposes, under the names it uses.

A world whose ground is flat has nowhere for water to rise to, and the panel says so directly — "This world is flat, so there is nowhere for water to rise to." — rather than offering a slider that would do nothing.

If you see that, sculpt some ground first — a basin, a valley, anything with a low point — and come back.