Nymphs are sentient creatures that, like Sirens, are almost always young and beautiful. Humanoid and female, nymphs are different than Sirens in their inherent, unique affinity to a particular natural environment, almost never venturing beyond their homeland habitat. As such, nymphs are usually categorised into subspecies by their natural terrain, such as sea nymphs, river nymphs, and forest nymphs. An example of a sea nymph is the Nereid, and the Dryad is a type of forest nymph.