*hehe* Looks like I'm good (or, in this case, lucky) at guessing them... But certainly not at making them.
Neverteless, one single try:
Find me in rivers, lakes and seas
For I am the single one who makes
them full of blue and clearest life
To find my name's your task. Now strive!
(Okay, the rhyme is not perfect... But I'm German

)