I would argue neither.
With the rising tide of modern science, historical criticism, and other scholarly disciplines, those committed to a strict literalist interpretation of the Flood stories in Gen 6-9 have had to retreat farther and farther up the metaphorical beach in order to maintain their belief in the historical reality of the Biblical tale. For instance, basic problems with a literal reading of the narrative include the fact that there is no geological evidence for a global flood, and that the Biblical Flood narrative in large part is derivative of an older Mesopotamian Flood story from the myth Atrahasis (among many other reasons). Sometimes, though, more liberal readers of the text suggest that the Flood was a historical event but that it was localized in a specific area, and that from the shortsighted view of the ancient author the whole land (including the mountains) indeed was covered with water. Thus we shouldn’t expect there to be evidence in the geological record for a global flood. However, there is, in my view, a more adequate understanding of the text, one that takes it on its own terms.
Israelite cosmology as it is reflected in the Bible basically consisted of a three-tiered world with the heavens/sky above, the earth below the sky, and the waters below the earth. In the heavens (which, for some authors, had multiple levels) the gods resided, while humans lived on the earth. Moreover, Israelites believed that there was water above the earth, presumably because the sky, like the sea, is blue and, moreover, rain would often come down from the sky. In this pre-scientific worldview there was a solid, clear (perhaps ice or crystal?) dome-like structure that prevented the waters above the earth from crashing down onto the earth. This material object is translated as “firmament” in the KJV in Gen 1. The so-called “windows” of heaven were, in their view, sluices cut into the dome through which YHWH would send down rain according to his providence. The sun and the stars were underneath this solid dome. Furthermore, pillars were sunk into the subterranean waters to support the earth, and below the earth was also She’ol, the underworld. Mountains, on the other hand, were thought by some to support the dome. For more visual readers, see HERE for a basic representation of this cosmological worldview.
Gen 1 describes creation as a divine process of organizing the world from the chaotic primeval waters by separating different elements so as to provide order. The Israelite God separates the waters using the dome in order to create the sky and then, within this “bubble,” proceeds to organize the rest of the world through separation and demarcation. Just as, on the social level, God separated the Israelites from the other nations and gave them his covenant and its attendant laws in order to organize their lives and provide them with well-being, so too, on the cosmological level, proceeded the creation of the world. The formation of the world, in a sense, mirrored the creation of Israel, and vice versa.
Thus it would seem somewhat unfair either to criticize or to validate – on scientific grounds – the author(s) of the Flood stories by measuring their texts against the ruler of modern scientific cosmology. The Flood stories do not comment upon whether the Flood was local or global in scientific terms; indeed, their view was pre-scientific. Rather, for the Israelites who authored these stories the Flood primarily represents “uncreation”: that is, the disorder and chaos that existed before God’s mastery over creation brought order. When sin filled the world the God of Israel unleashed the subterranean and heavenly waters to fill the bubble. So too if Israel transgressed its covenant and failed to keep the laws of YHWH their society would fall into chaos and ruin.