Let’s create list with names associated with water or have water as part of the meaning…I’ll start:
Girls:
[name]Kallan[/name] - flowing water
[name]Lake[/name]
[name]Ondine[/name]
[name]Talise[/name] - lovely water
[name]Tallulah[/name] - leaping water
Boys:
[name]Hudson[/name]
[name]Nalin[/name]
[name]Tahoe[/name]
[name]Twain[/name]
[name]Marina[/name]/[name]Marino[/name]
[name]Ilma[/name] (I believe this means water in Maltese - please correct me if I’m wrong!)
[name]Douglas[/name]
[name]Moses[/name] (taken from water)
[name]Aqua[/name]/[name]Aquarius[/name]
I also found the following link:
Girl:
[name]Aqua[/name]- means “water”
[name]Bay[/name]
[name]Laken[/name]
Boys:
[name]River[/name]
[name]Rio[/name]
I absolute adore [name]Ondine[/name] (and the original, [name]Undine[/name]) - just so beautiful, and with a literary connection.
@ Unicorngal - as a former Latin student, I feel the need to point out that [name]Aqua[/name] actually simply means ‘water’.
[name]How[/name] about the lovely [name]Lily[/name], as in water lily?
We’ve done this before, but it has been quite a while:
Girls
[name]Avalon[/name]
[name]Coral[/name]
[name]Cordelia[/name]
[name]Delphine[/name]
[name]Marina[/name]
[name]Nerissa[/name]
[name]Penelope[/name]
[name]Rainie[/name]
[name]Sailor[/name]
[name]Venice[/name]
Boys
Balboa
[name]Blue[/name]
[name]Dewey[/name]
[name]Drake[/name]
[name]Finn[/name]
[name]Jonah[/name]
[name]Kai[/name]
[name]Moses[/name]
[name]Noah[/name]
[name]River[/name]
[name]Wade[/name]
[name]Walden[/name]
Naiads were the ancient Greek water nymphs. Here are a few of their names:
Aigina / Aegina
[name]Daphne[/name]
[name]Dione[/name]
[name]Elektra[/name]
[name]Ismene[/name]
[name]Kyrene[/name] (Cyrene)
Lilaea
[name]Melia[/name]
Metis
Mideia
Neda
[name]Nemea[/name]
Thebe
Thespeia / Thespia
[name]Thisbe[/name]
Tiasa
[name]Sabrina[/name] (from the river Severn OR the name of the water goddess)
[name]Ocean[/name]/[name]Oceane[/name]
[name]River[/name]
Whaley (I actually went to school with a girl by this name)
Believe it or not my parents named me C. Waters! Duh, did they not hear the sound of my name?
Ha! [name]Rollo[/name] that’s funny!
My aunt’s name is actually [name]Wendy[/name] [name]Gail[/name] - my grandma didn’t catch it before naming her!
Oh, [name]Windy[/name] [name]Gale[/name] that’s a laugh too!
[name]Harbor[/name]
Moana ([name]Ocean[/name] in M?ori said Mor-wan-uh)
[name]Anemone[/name]
[name]Teale[/name]
[name]Waverley[/name]
[name]Cora[/name]
[name]Ariel[/name]
[name]Shelley[/name]
[name]Ulysses[/name]
[name]Oceane[/name]
[name]Oceania[/name]
Girls
[name]Sandy[/name] (can be girl or boy)
[name]Coral[/name]
[name]Lorelei[/name]
[name]Riviera[/name]
Boys
[name]Fisher[/name]
[name]River[/name]
[name]Rivers[/name]
[name]Fin[/name]
[name]Finn[/name]
[name]Elea[/name], I love your mythological spin on the water names! Since you’ve listed the Naiades, I’ll list the Artemisian Oceanides – those nymphs who were daughters of [name]Oceanus[/name] and attendants to the goddess [name]Artemis[/name], as mentioned in the [name]Roman[/name] poet [name]Ovid[/name]'s Metamorphoses:
Crocale - meaning “sea shore.”
Hyale - meaning “crystal.”
Phiale - meaning “water bowl.”
Psecas - meaning “rain shower.”
Rhanis - meaning “rain drop.”
[name]Nephele[/name] (!) - meaning “rain cloud.”
– [name]Nephele[/name]
a teacher at my daughters school is named Aquarelle it must be water related.
Girl - [name]Brook[/name], [name]Jordan[/name] (like the river)
Boy - [name]Reed[/name] (grows in water)
Great topic! 
[name]Aquarius[/name]
Cascada (waterfall)
[name]Dillon[/name]- born of the sea
[name]Frost[/name]
[name]Nahla[/name]
[name]Kai[/name]- hawaiian for ocean
[name]Troy[/name] means water
Mer
[name]Oceana[/name]
[name]Aphrodite[/name]
[name]Doris[/name]/[name]Doria[/name]
[name]Maleah[/name]
[name]Muriel[/name]
[name]River[/name]
[name]Raine[/name]
[name]Rainey[/name]
[name]Nile[/name]
[name]Jordan[/name]
Seine
The seven mermaid sisters in Disney’s The [name]Little[/name] Mermaid:
Aquata
[name]Andrina[/name]
[name]Arista[/name]
Attina
[name]Adella[/name]
[name]Alana[/name]
[name]Ariel[/name]