Encirclement as the serpent's resting posture: neither text has the serpent attack — Jormungandr simply lies around all the earth in the surrounding sea, mouth closed on his own tail; Ahi lies 'couched around the waters,' holding the goddesses 'encompassed.' In both, the coil is a form of custody — the serpent holds a whole category of the world (the dry earth, the celestial waters) enclosed within its ring, keeping rather than devouring, and the enclosure persists until an outside force (Ragnarok, the bolt) breaks it.
All-father 'threw the serpent into the deep sea which surrounds all lands. There waxed the serpent so that he lies in the midst of the ocean, surrounds all the earth, and bites his own tail' — the serpent's whole existence is a closed coil laid around the inhabited world.
Vritra smitten 'with flying weapon where he lay... and, godless, kept the goddesses [Griffith's note: the heavenly waters] encompassed'; Indra 'slewest Ahi showing his strength when couched around the waters' (vv. 6, 11).
Gylfaginning 34 verified verbatim in the Anderson translation; RV 3.32.6 and 3.32.11 verified verbatim in the Griffith scan including his note glossing 'the goddesses' as the heavenly waters.
Our fact-checkers corrected the first draft:
The identical test, posed and failed: the world-encircling sea-serpent hooked from a small boat, drawn up just far enough for a face-to-face look, and then lost.
The serpent as impounder of water: in both, the serpent takes the waters into its own keeping (encompassed under Vritra's bulk / swallowed into the Bakhu serpent's body), the world's motion stalls (the rivers penned like cattle / the solar barque standing still), and an armed god compels restitution · the waters are given back in full and flow resumes.
In both, heaven never announces the flood openly.
In both traditions repopulation after the flood is not biological but liturgical: the survivor's post-landing sacrifice is the literal manufacturing step for the next humanity.