Seeing the giantess Gjálp causing the water on Vimur river to rise, Thor used the magic staff to escape drowning, and then threw a rock at the giantess who fled. Thor and Loki arrived at the castle, where he was placed in a room with one chair. Weary from the travel, he sat down and closed his eyes. All at once, Thor was closing in on the ceiling. He thrust Gríðr's staff against the roof beam and pushed down. With the heavy weight and force of their guest, the giantess sisters, Gjálp and Greip, were crushed to death.