Water polygons representing the lake and river.Water areas are filtered and simplied acoording to scalerank and osm_area. At lowest zoom levels, it just has big lakes and give rivers.When you zoom in, more small water area should show up.

shape type : polygon

The 'class' field indicates the value of the water, the possible values are: 'ocean' , 'lake' , 'natural' , 'river' , 'pond' , 'pool' , 'reservoir' , 'basin' , 'canal' , 'lock' , 'swimming_pool' .