"spoke of her as el mar, which is masculine."

La mar ... or el mar?
Creative Commons Attribution Share AlikeLa mar ... or el mar? - Credit: rachel_thecat, Flickr
In Spanish nearly all nouns are either feminine or masculine, regardless of whether the entity has sexual characteristics or not. In general, feminine nouns end in -a and are referred to with the definite article la; masculine nouns end in -o and are referred to with the definite article el. (There are many exceptions to these rules.)

So, for example, the English word pen is la pluma in Spanish (feminine). Dog is el perro (masculine), regardless of whether the dog is male or female.

The Spanish word for sea, mar, "is usually masculine, but it becomes feminine in some weather and nautical usages (such as en alta mar, on the high seas)." Thus it is a "noun of ambiguous gender."