The giant who survived the flood from Ymir’s blood was Bergelmir.
In Norse creation mythology, Odin and his brothers Vili and Vé kill the primordial jötunn Ymir. The blood pouring from Ymir’s wounds becomes a catastrophic flood that drowns nearly all the frost giants. Bergelmir escapes with his unnamed wife aboard a lúðr, a term that may mean a chest, trough, cradle, or boat-like vessel.
Bergelmir is more than a survivor in the Prose Edda: he becomes the ancestor of a renewed race of frost giants. His family line is also given in Vafþrúðnismál, where he is identified as the son of Þrúðgelmir and grandson of Aurgelmir, another name associated with Ymir.
A common mix-up is to treat the flood as a separate event from the gods’ creation of the world. In the myth, it follows directly from Ymir’s killing, and his body is then used to form the earth, sea, mountains, sky, and Midgard.