High Water 256

Summary

Floods the Overworld to y=256 — survive an endless ocean, with a custom advancement tab.

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A data pack that turns the Overworld into one giant ocean. Sea level is raised to y=256 and aquifers are disabled, so water fills everything below it. Vanilla terrain and biomes still generate — they're just submerged. Mountains become rare underwater ridges; dry land is gone.

Built for boat survival, "ocean only" challenges, and hardcore runs where every block of dirt is precious.

Nothing but ocean

Features

• 🌊 Flooded world — sea level 63 → 256, aquifers off, uniform global ocean.
• 🏝️ Vanilla terrain & biomes, fully submerged.
• 🚫 No floating land structures — villages, pillager outposts, witch huts, igloos, desert pyramids, jungle temples, woodland mansions, ruined portals and abandoned camps are disabled.
• 🚢 Underwater & buried structures still spawn — shipwrecks, ocean ruins, trail ruins, ocean monuments, buried treasure, and all underground structures.
• 🟩 Wandering Trader sells grass blocks (1 emerald → 4), so dirt isn't impossible in a world with no land.
• 🏆 Custom advancement tab "High Water" — 20 themed advancements (get a trident, tame a nautilus, reach the lava layer, build a Nether portal, survive 100 days, and more).

The Modrinth download contains English advancement text. Install only one version of High Water in a world.

Installation (apply when CREATING the world)

World-generation settings are locked in at world creation — adding the pack to an existing world will not flood it.

1. Singleplayer → Create New World → More → Data Packs.
2. Drag the chosen .zip onto the screen and move it to the Selected column.
3. Create the world — you'll spawn underwater.

(The advancements & trade also work on an existing world via /reload; only the flooding/structures require a fresh world.)

Upgrading an existing High Water world

Make a backup, replace the old pack with version 1.1.0, and fully restart the world in Minecraft 26.3. Existing chunks keep their blocks; new chunks use 26.3 generation and may differ at chunk borders.

Recommended seed

In Minecraft 26.2, seeds -322026680007972738 and 8960963892627342880 had a shipwreck near spawn. The shipwreck locations have not been rechecked in 26.3.

Tips

• Lava & obsidian: with aquifers off, caves are water-filled from y=-54 up to y=256. Natural lava only exists below y=-54 (just above bedrock). Dig down to ~y=-55, then pour water on the lava to make obsidian.

Compatibility

• High Water 1.1.0: Minecraft Java Edition 26.3 (data pack format 121.0).
• High Water 1.0.0: Minecraft Java Edition 26.2 (data pack format 107.1); available in the Versions tab.
• Server-side / world-gen only — no client mod required. Works in vanilla and with Fabric / Sodium / Iris.