Heavenly Downpour

All non-Mountain lands are Islands in addition to their other types.
Creatures without flying or islandwalk can't attack.
"When the gods heard our pleas, they chose to seal away not only Ganon, but Hyrule itself...and so, with
a torrential downpour of rains from the heavens... Our fair kingdom was soon buried beneath the waves."
- Daphnes Nohansen Hyrule