|Whirlpool as seen on the Adventure Map.|
Whirlpool is an Adventure Map object, that can only be located on water terrain. It can only be entered with a hero traveling on boat, and it instantly transfers the hero (and the boat) to another randomly chosen whirlpool. If there is only one whirlpool in the map, it does not transfer hero anywhere but it will still cause the hero to lose part of their army.
When a hero enters the whirlpool, he loses 50% rounded down of the creatures in his army's weakest stack. The weakness is determined by total health of the stacks. With Sea Captain's Hat or Admiral's Hat (only in Shadow of Death), a hero can enter whirlpools without losing creatures. To avoid losses, a player may divide one of the most disposable troop to an individual slot, which naturally becomes the weakest stack and is therefore lost during the transfer. If a hero with only one creature enters a whirlpool, the creature will not be lost, making whirlpools "safe" for scouting heroes.
Whirlpool consists of six squares which can be used to enter or exit the whirlpool. The exit square is selected randomly which may lead to a situation, where the boat cannot move outside the whirlpool squares after the teleportation. Note that the space key can be used in the Armageddon's Blade and Shadow of Death expansions to re-enter the current square to avoid unnecessary movement.