Oceanides, Nereides, and Naiades

The worship of water-deities is common to most primitive nations. The streams, springs, and fountains of a country bear the same relation to it which the blood, coursing through the numberless arteries of a human being, bears to the body; both represent the living, moving, life-awakening element, without which existence would be impossible. Hence we find among most nations a deep feeling of attachment to the streams and waters of their native land, the remembrance of which, when absent in foreign climes, is always treasured with peculiar fondness. Thus among the early Greeks, each tribe came to re- gard the rivers and springs of its individual state as beneficent powers, which brought blessing and prosperity to the country. It is probable also that the charm which ever accompanies the sound of running water exercised its power over their imagination. They heard with delight the gentle whisper of the fountain, lulling the senses with its low, rippling tones; the soft purling of the brook as it rushes over the pebbles, or the mighty voice of the waterfall as it dashes on in its headlong course; and the beings which they pictured to themselves as presiding over all these charming sights and sounds of nature, corresponded, in their graceful appearance, with the scenes with which they were associated.

Oceanides
The O, or Ocean Nymphs, were the daughters of Oceanus and Tethys, and, like most sea divinities, were endowed with the gift of prophecy.
They are personifications of those delicate vapour-like exhalations, which, in warm climates, are emitted from the surface of the sea, more especially at sunset, and are impelled forwards by the evening breeze. They are accordingly represented as misty, shadowy beings, with graceful swaying forms, and robed in pale blue, gauze-like fabrics.

The Nereides
The N were the daughters of Nereus and Doris, and were nymphs  ofthe Mediterranean Sea.
They are similar in appearance to the Oceanides, but their beauty is of a less shadowy order, and is more like that of mortals. They wear a flowing, pale green robe; their liquid eyes resemble, in their clear depths, the lucid waters of the sea they inhabit; their hair floats carelessly over their shoulders, and assumes the greenish tint of the water itself, which, far from deteriorating from their beauty, greatly adds to its effect. The Nereides either accompany the chariot of the mighty ruler of the sea, or follow in his train.
We are told by the poets that the lonely mariner watches the Nereides with silent awe and wondering delight, as they rise from their grotto-palaces in the deep, and dance, in joyful groups, over the sleeping waves. Some, with arms entwined, follow with their movements the melodies which seem to hover over the sea, whilst others scatter liquid gems around, these being emblematical of the phosphorescent light, so frequently observed at night by the traveller in southern waters.
The best known of the Nereides were Thetis, the wife of Peleus, Am- phitrite, the spouse of Poseidon, and Galatea, the beloved of Acis.

The Naiades
The N were the nymphs of fresh-water springs, lakes, brooks, rivers, &c. As the trees, plants, and flowers owed their nourishment to their genial, fostering care, these divinities were regarded by the Greeks as special benefactors to mankind. Like all the nymphs, they possessed the gift of prophecy, for which reason many of the springs and fountains over which they presided were believed to inspire mortals who drank of their waters with the power of foretelling future events. The Naiades are intimately connected in idea with those flowers which are called after them Nymphæ, or water-lilies, whose broad, green leaves and yellow cups float upon the surface of the water, as though proudly conscious of their own grace and beauty.
We often hear of the Naiades forming alliances with mortals, and also oftheir being wooed by the sylvan deities of the woods and dales.