Ice Palace

The Ice Palace (氷の塔, Ice Tower) is the fifth dungeon of the Dark World in A Link to the Past.

Entrance to the Palace
It is located in the Southeast, in the middle of the large lake. Access to the dungeon is granted by swimming to the largest island in the Light World. Lifting up the black rock (which requires collection of the Titan's Mitt in Thieves' Town) reveals a portal; Link must step on it to be teleported outside Ice Palace entrance.

Themes and Navigation
The Ice Palace is possibly the first ice-themed dungeon in the Zelda series, followed six years later by the Ice Cavern from Ocarina of Time. As such, the ground is frozen in most rooms, making Link's traction more difficult. It contains numerous floors as well, although none of them have too many rooms, and the main objective is to descend to the last floor, where the boss resides. Link frequently has to move blocks that obstruct his way, and some creatures can only be defeated with the Fire Rod. This dungeon is considered to be one of the most difficult in the game, although one of its rooms has its complexity lowered in the Game Boy Advance remake. The main treasure is the Blue Mail, a tunic that increases Link's physical defenses. The Palace's boss is Kholdstare, a living formation of ice. After defeating the boss, Link receives a Heart Container and the 5th Crystal.

Trivia

 * It is interesting to note that the Ice Palace goes entirely underground.