Symbolism, Imagery, Allegory
Like many other Shakespeare plays (The Comedy of Errors, Pericles, etc.), Twelfth Night is full of images and allusions to the sea. It's the place where the twins, Viola and Sebastian, are literally separated when their ship "splits" and sinks, which is the driving force of the plot. While the ocean is a wide and dangerous place where families can be destroyed and lives can be lost, the play offers a hopeful point of view. In one of the first vivid allusions to the ocean, the sea captain offers a stunning image:
I saw your brother,
Most provident in peril, bind himself,
Courage and hope both teaching him the practise,
To a strong mast that lived upon the sea;
Where, like Arion on the dolphin's back,
I saw him hold acquaintance with the waves
So long as I could see. (1.2.3)
In this vivid description of Sebastian's elegance and bravery in the face of a pretty harrowing experience, the ocean becomes a "sink or swim" metaphor for life. In tough situations, one can either drown or ride out stormy moments with the ease of "Arion" moving through "waves" on a "dolphin's back." (Did that just come from the mouth of a sailor? You see, this is why we love Shakespeare. Instead of cursing, this sailor sounds like an eloquent handbook for life's difficult moments.)
Before we get too sentimental, we have to acknowledge some other, less gorgeous allusions to the ocean. In Act 1, Scene 1, Valentine calls Olivia's tears (shed for her dead brother) "eye offending brine." Brine, of course, is a salty fluid that's synonymous with tears and, you guessed it, the ocean. Here's the gross part. Valentine also says that Olivia's salty tears keep her dead brother's memory alive and "fresh," which sort of creates an image of Olivia preserving or, pickling her dead brother.
Hungry as the Sea
So, you're probably wondering how you can connect the play's representation of the ocean to food imagery. Here's an idea. Why not think about the way Duke Orsino compares his appetite for love to the ocean? When Orsino claims that women aren't capable of passion, he says that his love "is all as hungry as the sea, / And can digest as much" (2.4.16). Here, the ocean becomes a simile for the Duke's voracious and insatiable erotic "appetite." This is funny and also a little scary – we get the sense that Orsino's passion could swallow a person whole.