Now to show you my two theories of Ophelia's death

Ophelia was pregnant and saw no way out but to get rid of her child. Shakespeare often tells a story within a story. I think Ophelia's secret pregnancy was just that. Which is why Shakespeare made a point to mention Rue repeatedly. Ophelia had lost everything, her father, her lover, and her virginity. All one has is there reputation, and for Ophelia, it was worth risking her life over to preserve. While hanging flowers to dry, I think Ophelia ate the rue herb to have an abortion. Unfortunately as i discussed before, it is very easy to miscalculate the proper dosage. I think the sedative poisioned her and as the branch broke she fell into the water, where helplessly drowned. It is ironic that Ophelia was helpess in the water, or as Gertrude described it, "one incapable of her own distress" because Ophelia's name in Greek is translated to mean "help."

Now for my second theory...Ophelia could have been murdered. And by someone who everyon thought was "on their side." Gertrude describes the death of Ophelia to Laretes as,

There is a willow grows aslant a brook, That shows his hoar leaves in the glassy stream; Therewith fantastic garlands did she make Of crow-flowers, nettles, daisies, and long purples That liberal shepherds give a grosser name, But our cold maids do dead men's fingers call them: There, on the pendent boughs her coronet weeds Clambering to hang, an envious sliver broke; When down her weedy trophies and herself Fell in the weeping brook. Her clothes spread wide; And, mermaid-like, awhile they bore her up: Which time she chanted snatches of old tunes; As one incapable of her own distress, Or like a creature native and indued Unto that element: but long it could not be Till that her garments, heavy with their drink, Pull'd the poor wretch from her melodious lay To muddy death. (4.7.166-183)

How would Queen Gertrude have known so many details? Horatio. Horatio was ordered to follow Ophelia by King Claudius. Therefore, he would have witnessed the entire event. Why didnt he save her? Lets look back at Horatio...

Horatio was playing both sides. He was obeying the King and obeying Hamlet. When Hamlet sends a letter to the King and Queen by sailors. Horatio intercepts the letter when he is alone. Hamlet did not want a third-party involved and yet instead of following Hamlet's instructions to take the sailors to the King and Queen, the letter arrived by messenger. The messenger recieved the letter from Horatio (Claudio). And Shakespeare makes a point to emphasize that the messenger never saw any sailors.
What is he playing at??

When Ophelia was spouting songs in her madness, King Claudius orders Horatio to "Follow her close; give her good watch, I pray you." So Horatio would have been with Ophelia at her death. Unfortunately, we will never know if he had a hand in killing her. Or if he stood idly by as she drowned.