Sandbars are ridges of sand that run adjacent to the coast or emerge from it (such as from a point or peninsula). Sand bars may be submerged beneath shallow water or may be exposed and dry. The state of the tides (high tide versus low tide) may determine their depth in the water or exposure to the surface. In fictional worlds sand bars may act as minor land bridges, connecting the mainland to islands or other areas. This connection may be subject to the tides and moon.