A local nature reserve situated to the north of Glenrothes in Fife, Coul Den represents the remains of Coul Reservoir with a network of paths through developing natural habitats, including willow scrub, grassland and marsh. Designated in 2000, the reserve extends to 10.7 ha (26.5 acres). Popular with local walkers, the reserve provides a breeding site for birds including Mute Swans, Coot, Moorhen and Little Grebe. It is also home to frogs, toads and newts, together with dragonflies, damselflies and butterflies. There are also a variety of plants of local and national importance including Ragged Robin and Common Spotted Orchid.
Coul Den is managed by Fife Coast & Countryside Trust.