You can speak, read, and write Common and Sylvan. Some Dryads that deal with druids folk know Druidic themselves.

Your creature type is both fey and humanoid. Given that your physiology is primarily composed of water, you are vulnerable to cold damage.

Resistant to Being a water-based life form, you are resistant to bludgeoning, slashing, and piercing damage but are vulnerable to lightning and poison damage. You can use your action to give yourself a human appearance but you forfeit your resistances, until you choose to go back to your water form.

 You age very slowly, which means you can live anywhere from a few hundred years to a few thousand.

Water Dryads tend to be lawful and are rarely evil, following and protecting the ways of their realms.

Dryads come in many sizes, ranging from under 6 feet to almost 14 feet tall. 

25 walking speed. 40 swimming speed.

your intelligence score increases by 2.

exchanging a number of spell slots equal to racial spell alongside 1D10 damage to the caster, allows casting of a single spell of a high water elemental one every long rest.

Naiads reach mental and physical maturity around age 100 where they are now able to bond to their chosen tree. They are immortal for as long as their bonded tree is still alive, but they can still be wounded to the point of falling unconscious. While unconscious, they will slowly heal themselves, which can take weeks up to years depending on the severity of the injuries. Before falling unconscious, a naiad's state will determine whether they stay in their physical form or turn to water. Once they pass out, they cannot change forms until they wake up. If they are in their physical form, they will stay where they are until they wake up from substantial. If they are in the form of water, they will absorb into the earth to find their way back to their source. Once there, the healing process is sped up exponentially. They leave their unconscious state when their body has healed itself on its own or when someone else heals them.

You have advantage on saving throws against being charmed, and magic can’t put you to sleep.