A lake is a naturally occurring, relatively large body of water localized in a basin surrounded by land, with much slower-moving flow than any inflow or outflow streams that serve to feed or drain the lake. Lakes lie completely on land and are separate from the ocean, although, but like the much larger oceans, they form part of the Earth's water cycle by serving as large standing water reservoirs. Most lakes are freshwater, but some are salt lakes with salinities even higher than that of seawater. Lakes are typically much larger and deeper than ponds, which also water-filled basins on land, although there are no official definitions or scientific criteria distinguishing the two. Most lakes are both fed and drained by creeks and rivers, but some lakes are endorheic without any outflowing drainage, while volcanic lakes are filled directly by precipitation runoffs and do not have any inflow streams.