There are many sources that mentioned about her being related to the sea, even the salt sea.

Tiamat is the Mesopotamian goddess associated with primordial chaos and the salt sea best known from the Babylonian epic Enuma Elish. - ancient.eu

In the religion of ancient Babylon, Tiamat is a primordial goddess of the sea, mating with Abzû, the god of the groundwater, to produce younger gods. She is the symbol of the chaos of primordial creation. She is referred to as a woman,[4] and described as "the glistening one."[5] It is suggested that there are two parts to the Tiamat mythos, the first in which Tiamat is a creator goddess, through a sacred marriage between different waters, peacefully creating the cosmos through successive generations. In the second Chaoskampf Tiamat is considered the monstrous embodiment of primordial chaos. Some sources identify her with images of a sea serpent or dragon.Wiki

However, Which sea is she related to? Persian Gulf or Mediterranean Sea?. How was the perception of Ancient Babylonian people toward the sea?

And Formerly, she is just mother goddess with no mention about her appearance as being serpent at all? When and why she has been transformed in to serpent?