Teleportal
From Dragon Quest Wiki
A travel gate is method of transportation in Dragon Quest games. It is represented by a tile of water which looks similar to a whirlpool. By stepping onto the tile, the Hero's party will be transported to another location. Most often, travel gates are bi-directional, meaning the Hero's party can travel in both directions. Travel gates first appeared in Dragon Quest II.
Travel gates have served a variety of uses in the Dragon Quest games. These include transporting the Hero's party to a distant location early in the game before having another means of long distance transportation (ship, Return spell), giving access to a remote location which is not accessible by other means, or as part of a maze within a castle/dungeon.