Otherside Portal
The Otherside Portal is a dimensional gateway added by the Deeper and Darker mod that transports players to The Otherside, a dangerous new dimension beneath the 
Bedrock. Building and activating this portal requires defeating the Warden to obtain the 
Heart of the Deep, making it a late-game progression milestone.
Unlike the Nether Portal, which uses 
Obsidian and 
Flint and Steel, the Otherside Portal requires a frame made of 
Reinforced Deepslate and must be activated with the Heart of the Deep. The most accessible frame is found pre-built in Ancient Cities, though players can construct their own frames of varying sizes.
Building
The Otherside Portal frame must be constructed from Reinforced Deepslate, an unbreakable block found exclusively in Ancient Cities. The interior of the portal (not counting the frame) can range from 2×2 to 48×24 blocks, giving players flexibility in portal size.
Ancient City Frame
The easiest way to access The Otherside is by using the pre-built portal frame in Ancient Cities. This frame measures 22 blocks wide by eight blocks tall (interior dimensions) and is located in the central structure of the Ancient City, constructed from the Reinforced Deepslate archway.
Look for the large Reinforced Deepslate structure in the center of the Ancient City. The portal frame is the rectangular archway. Ancient Cities generate in the Deep Dark biome, typically found at Y-level -52 or below.
Custom Frames
Since Reinforced Deepslate cannot be broken in Survival mode, building custom portal frames requires Creative mode or commands. However, once placed, the portal mechanics function identically to those of the Ancient City frame. Custom frames must have a minimum interior size of 2×2 blocks.
Activation
Activating the Otherside Portal requires the Heart of the Deep, a guaranteed drop from the Warden. Right-click on any block of the Reinforced Deepslate frame with the Heart of the Deep to ignite the portal. The Heart is not consumed during activation, allowing you to light multiple portals with a single Heart.
Sculk blocks attached to the portal frame will prevent activation. Before using the Heart of the Deep, clear all Sculk, 
Sculk Veins, and 
Sculk Catalyst blocks from the Reinforced Deepslate frame. The frame surface must be completely clear for the portal to ignite.
Once activated, the portal displays a teal-colored swirling effect and emits an eerie ambient sound. The portal remains active indefinitely unless destroyed by breaking the frame blocks (only possible in Creative mode).
Travel
The Otherside Portal functions similarly to the Nether Portal. Stand inside the portal for a few seconds to teleport to The Otherside. Unlike the Nether, The Otherside has a 1:1 coordinate ratio with the Overworld; traveling 100 blocks in The Otherside moves you 100 blocks in the Overworld.
When you first enter The Otherside, a new portal generates at your destination. Returning through this portal brings you back to your original Overworld portal. If your return portal is destroyed or you become lost, death is the only way to return to the Overworld.
Write down your portal coordinates before exploring The Otherside. The dimension is vast and dangerous, and losing your portal location means you cannot return home except by dying. There is no 
compass or 
map functionality to help locate portals in The Otherside.
Preparation
The Otherside is extremely dark with an ambient light level of only 0.05. Without proper equipment, the permanent Darkness effect makes exploration nearly impossible. The 
Warden Helmet negates the Darkness effect and is considered essential before entering The Otherside.
Bring sufficient supplies, including food, building blocks, torches, weapons, and armor. The dimension contains hostile mobs, including Sculk Centipedes, Sculk Snappers, Shattered, and even the Warden can spawn naturally. The dimension has a ceiling at Y=128 and perpetual twilight (a fixed time of 18000 ticks).
Frequently Asked Questions
Obtain the Heart of the Deep by killing the Warden, then right-click on the Reinforced Deepslate portal frame with the Heart. Make sure to clear any Sculk blocks from the frame first, as they prevent activation.
Sculk blocks on the portal frame prevent activation. Clear all Sculk, Sculk Veins, and Sculk Catalyst blocks from the Reinforced Deepslate frame surface. Also ensure you’re clicking directly on the frame blocks, not adjacent blocks.
No, the Heart of the Deep is not consumed. You can use the same Heart to activate multiple portals and keep it afterward for crafting the 
Sonorous Staff or using its heartbeat detection ability.
In Survival mode, no—Reinforced Deepslate cannot be obtained or broken. In Creative mode, you can place Reinforced Deepslate to build custom frames with interior dimensions from 2×2 up to 48×24 blocks.
Essential: Warden Helmet (negates Darkness effect), full armor set, weapons, food, building blocks, and torches. Recommended: 
Golden Apples, 
Ender Pearls for escape, and materials to write down coordinates. The dimension is very dark and hostile.
Return through the portal that generated when you arrived. The portal works bidirectionally like a Nether Portal. If you lose your portal, death is the only way back—record your portal coordinates before exploring!
