pertanyaan about nw moon the movie

just had a thought...
in new moon after bella has cliff dived and she sees victoria swimming towards her and she bangs her head on the rocks...where did victoria go?

she was swimming fast towards her and then bella bangs her head and is floating "with edward" for like 1 menit before jacob pulled her out...wouldnt victoria have been able to swim to her in that menit and kill her ? what made her disapear? it couldnt havae been jacob coz she could have killed him too...since she has the advantage of not needing to breathe underwater