Beowulf dives into the mere wearing his mail-shirt and carrying Hrunting in its scabbard. Deep in the lake, the mother grasps him tightly with her claws so that he cannot draw his sword. The mail-shirt protects him even though various water-beasts thrust at him as the mother carries Beowulf to an underwater cave, which is dry and lighted by "glaring flames" (1517). Once there, Beowulf manages to mount an attack, but Hrunting is ineffective against the ogre's tough hide. Beowulf then tries to wrestle her, but he fails to gain the kind of death grip that defeated Grendel.
Although she is knocked down, the mother immediately counters Beowulf's attack and soon is sitting on him. She pulls her knife, but it cannot pierce his mail-shirt. Again on his feet, Beowulf spots a huge sword made by giants. Although he can barely lift it, he manages a mighty blow that severs the mother's spine at the neck, killing her. A blessed light suddenly illuminates the cavern, revealing Grendel's corpse. Beowulf lops off the head to replace the trophy of the claw that the mother retrieved.
Amazingly, the giant sword melts except for the hilt, which Beowulf carries along with Grendel's head as he returns to the surface of the mere. Only his Geats await him. Thinking him dead, Hrothgar and the Danes have returned to Heorot.
