Water Nymphs (Disney's Hercules)

Water Nymphs are a race of female water spirits.

River Nymphs
A Naiad reside on Phil's Island bathing with an Oread and a Dryad. Philoctetes enjoys spending his time peeping on these female spirits. They flee at his arrival.

In Hercules and the River Styx. Styx is technically a Naiad, or fresh-water nymph.

Sea Nymphs
Oceanids or Nereids reside on tropical islands and are in service to Gegenius, a giant monster who spares their lives in exchange for the life of sailors they lure to the island.

Trivia

 * In Once Upon a Time, any Nymph appears. However, Rumplestiltskin mention he had a pact with a sea nymph, implying their existence in the Enchanted Forest.