Ground is the default terrain in the Splatoon series.
The main ground type is concrete, though wood is also used such as large boxes, crates, planks, and logs. Ground is not seen or available in water, air, dirt, or pits.
Standard ground can be inked by Inklings to cover turf. Covering the ground is the primary objective of Turf Wars. Ground can be both walked on in human form, or swam in after covering it with ink in swim form, or swam on even without ink in swim form.
An example of concrete ground in Ancho-V Games.
An example of ground in Arowana Mall. The stage's ground is mostly concrete with a wooden ramp on either side of the center.
An example of ground in Kelp Dome. The ground is dirt and concrete with elevated metal platforms and ramps.