Edmund should not mess around with the portal device. He knows this! Zana (the cartographer, not the witch) has been very clear that he is not to touch the damn thing unless she's within arm's length. But he wasn't doing anything when it started whirring, and oscillating, and going faster and faster until it was going faster than it's supposed to and suddenly boom, he's hurtling through the fathomless void.
He lands with a crash. It mostly gets absorbed by his shielding. He picks himself up gingerly and looks around. Cliffs, jungle, ocean... nearby village? Well, nearby, it's a few miles off and down a cliff from him, but. He's been in worse situations, certainly.
...wait. Is that... there's some kind of bulge in the water? Is there a tsunami coming?