The Skull Cavern is in the northwest part of the Desert. It’s locked at first and you need a Skull Key to get in.

Skull Cavern in Stardew Valley
Skull Cavern Entrance

In the Skull Cavern, there are many floors with no limit. You move to the next floor by finding a ladder or a hole. There are no elevators like in the Mines, but you can leave the Skull Cavern from any floor using a ladder at the entrance. Sometimes, instead of a ladder, a hole appears and you can drop down multiple floors at once, between 3 and 15 floors.

The number of floors you drop is determined by chance, and it doesn’t depend on your Luck. However, if you drop down a hole that goes past floor 100, you will only be taken to floor 100 to avoid going beyond the game’s limit. Jumping down a hole also causes some Health damage, but it won’t reduce your Health to less than 1.

How to unlock Skull Cave in Stardew Valley

Iridium Drop

As you go deeper into the Skull Cavern, your chances of finding Iridium Ore increase gradually, especially at levels 10+ and 100+. The monsters in the Cavern can also drop ore, Iridium Bars, and special items, so be prepared with powerful weapons like the Lava Katana or Galaxy Sword.

Having high Luck increases the likelihood of finding ladders or holes that take you to lower levels. It’s often more efficient to quickly descend to floors with higher chances of spawning Iridium Nodes rather than exploring each floor. You can also stack staircases in your inventory, with each slot holding up to 999 staircases. However, even with staircases, descending blindly can still take time, as the lower you go, the less time you have to explore the Caverns.

Time inside Skull Cave

Time passes more slowly in Skull Cavern compared to other areas in the game. In Skull Cavern, one hour of game time lasts for 54 seconds, which is 25% longer than the normal 43 seconds. However, in multiplayer games and on Prehistoric Floors, time reverts to the normal 43-second hours.

Qi’s Challenge

After you enter the Skull Cavern for the first time, you will receive a letter from Mr. Qi the next day. The letter starts the quest called “Qi’s Challenge,” which requires you to reach floor 25 in the Cavern. If you complete the quest, you will receive 10,000g, which will be delivered to you by mail the day after you complete the quest. If you manage to reach level 25 of the Skull Cavern during your first visit, the quest will be automatically completed the next day.

Qi’s Hungry Challenge

“Qi’s Hungry Challenge” is a repeatable Special Order that you can accept in Qi’s Walnut Room on Ginger Island. To complete this quest, you need to reach floor 100 of the Skull Cavern within a specified time limit. However, while this quest is active, you won’t be able to consume any food or drink items while inside the Skull Cavern, although buffs from food or drink consumed before entering the Cavern will remain active.

During this quest, Big Slimes in the Skull Cavern may occasionally drop hearts that give you 10 health points when defeated, providing a way to regain health without eating. Another strategy is to equip Vampire Rings or use a weapon with the Vampiric enchantment to regain health. You are allowed to use staircases to descend floors. If you successfully complete the quest, Qi will reward you with 25 Qi Gems.

Skull Cavern Invasion

The ‘Skull Cavern Invasion’ is a repeatable Special Order that you can accept in Qi’s Walnut Room on Ginger Island. To complete this quest, you need to reach floor 100 of the Skull Cavern within a specified time limit. However, during this quest, you’ll encounter stronger variations of monsters in the Cavern, similar to the Dangerous Mines. Additionally, radioactive nodes may also spawn in the Skull Cavern, just like in the Dangerous Mines.

You are allowed to use staircases to descend floors. If you successfully complete the quest, Qi will reward you with 40 Qi Gems.