"lovely water-lilies round her, like Ophelia"

Ophelia is a young noblewoman of Denmark in William Shakespeare's play Hamlet.

A potential bride for Hamlet, she suffers a tragic fate. In seeking to uncover the truth about his own father's murder, Hamlet kills Ophelia's father. Grief drives her mad and she drowns.  Queen Gertrude reports that she climbed into a willow tree and a branch broke, causing her to fall into a brook. The other characters suspect Ophelia actually committed suicide. 

GERTRUDE

There on the pendant boughs her coronet weeds

Clamb'ring to hang, an envious sliver broke,

When down her weedy trophies and herself

Fell in the weeping brook.

                                    – Hamlet Act IV, Scene 7

The death of Ophelia became a popular romantic subject, most famously in this painting by John Everett Millais.