Create: Deep Seas - Lava Fix

Create: Deep Seas - Lava Fix

A small NeoForge mod for Minecraft 1.21.1 that fixes a bug in Create: Deep Seas (CDS) where players inside a hermetically sealed submarine still take fire/lava damage while the submarine is submerged in lava, even though CDS correctly empties the interior of lava.

> Author: Diyksfol > License: MIT > Note: This mod was developed with the help of an AI assistant; my own role was primarily that of a tester and director. The full source is provided here so anyone — including the Create: Deep Seas authors — may study, reuse, or integrate it.

---

What it fixes

In Create: Deep Seas, a sealed submarine can pump out all fluid (including lava) from its interior, letting you move around inside as if in open air. However, the game's damage code still applied fire/lava damage to players standing in that "emptied" space, because the damage checks did not account for the sealed sub.

This mod detects when a player is inside (or climbing out of) a sealed compartment and suppresses the fire/lava damage and the on-screen fire overlay in that case.

Specifically fixed

• Fire/lava damage while standing inside a sealed, lava-submerged submarine.
• Damage while standing in hatches/doorways at the lava surface (entry/exit).
• Damage while seated (Create seats), on ladders, or in doorways inside the sub.
• Endless fire ticks after the hull is breached and then re-sealed.
• The persistent fire overlay (flames at the bottom of the screen) while inside.

---

What it does NOT fix (and why)

These behaviours are internal to Create: Deep Seas. Fixing them from an external mod would require overriding core CDS systems and risks breaking the sealed-sub mechanic itself, so they are intentionally left alone:

1. Lava surface texture is still visible inside the sub. CDS hides the water

surface visually but not lava. This is a CDS rendering matter.

1. **Trapdoors don't work as climbable "ladders" when below the lava/water level

inside the sub.** CDS hides the fluid, and vanilla's trapdoor-climb mechanic depends on a fluid being present, so the climb is disabled. Same effect occurs with water in CDS.

1. Fire placed by the player inside the sub causes a fluid-like effect. Standing

in that fire applies slowness and, over lava, burning. This is a CDS interaction.

1. Lava or water poured directly inside the sub deals no damage / no drowning.

This is a deliberate CDS feature (the interior is treated as sealed), not a bug.

1. Mobs and animals inside the submarine still take fire/lava damage. The fix only protects the player. Other entities are not covered — do not keep animals or passive mobs inside a lava-submerged submarine.
2. The pressure system does not work under the lava.

If the Create: Deep Seas authors wish to address any of the above, they are welcome to use this code as a starting point.

---

Installation (players)

1. Install NeoForge for Minecraft 1.21.1.
2. Install Create: Deep Seas

and its dependencies (Create, Sable, etc.).

1. Drop submarinefix-1.0.1.jar into your mods/ folder.
2. Launch the game. That's it.

The mod is safe to install even without Create: Deep Seas — it simply does nothing in that case.

---

Building from source (developers)

This repository contains the uncompiled source. To build the jar yourself:

Prerequisites

• JDK 21
• The Create: Deep Seas jar and the bundled Sable Companion jar (used as

compile-only references — they are not redistributed here).

Steps

1. Clone this repository: https://github.com/Diyksfol/create-deep-seas-lava-fix
2. Create a libs/ folder in the project root and place two jars in it:

• create_submarine-2.1.6.jar — from your Create: Deep Seas download.
• sable-companion-common-1.21.1-1.5.0.jar — extracted from the CDS jar's

META-INF/jarjar/ folder (CDS bundles it).

Your build.gradle already references these via compileOnly files(...):

   compileOnly files('libs/create_submarine-2.1.6.jar')
   compileOnly files('libs/sable-companion-common-1.21.1-1.5.0.jar')

If your CDS version differs, update the filenames in build.gradle accordingly.

1. Build:

   ./gradlew build

On Windows:

   .\gradlew.bat build

1. The compiled jar will be in build/libs/.

> These jars are third-party and are intentionally not included in this > repository. You must supply them yourself from your own Create: Deep Seas install.

---

How it works (technical overview)

The fix combines several layers:

• LivingIncomingDamageEvent (server, primary): cancels incoming

LAVA / IN_FIRE / ON_FIRE / HOT_FLOOR damage when the player is inside a sealed compartment.

• Entity#baseTick mixin (server): suppresses the lavaHurt() call.
• LocalPlayer#baseTick mixin (client): suppresses the client-side

lavaHurt() so no fire ticks are produced locally.

• ScreenEffectRenderer#renderFire mixin (client): hides the fire overlay

while inside the sub.

• PlayerTickEvent.Post (server): clears any residual fire ticks each tick.

Detection

To decide whether a player is "inside a sealed sub", the mod: