How to Make and Use a Conduit in Minecraft

Guide Java Bedrock

Quick answer: Craft 1 conduit with 1 heart of the sea surrounded by 8 nautilus shells. Waterlog it at the center of a 3 by 3 by 3 water volume, then add 16-42 full prismarine-family blocks or sea lanterns in valid frame positions. Its player-effect radius is 32-96 blocks; only a complete 42-block frame attacks wet hostile mobs within 8 blocks.

What you need

1 Heart of the Sea (buried treasure)
8 nautilus shells
16-42 prismarine / sea lantern / dark prismarine blocks
Everything underwater

Step by step

Get a heart of the sea: it is found only in buried treasure chests, whose location is marked with a red X on a buried treasure map from ocean ruins and shipwrecks.
Get nautilus shells: drowned holding one always drop it (3% in Java, 8% in Bedrock), nautiluses rarely drop it, and you can fish it up.
Craft 1 conduit: place 1 heart of the sea in the center of a crafting table and 1 nautilus shell in each of the 8 surrounding slots.
Place the conduit in the center of a 3x3x3 volume of water (the conduit waterlogged too), enclosed by a frame of three 5x5 open squares, one around each axis.
Use full prismarine, dark prismarine, prismarine bricks or sea lantern blocks in valid frame positions. Slabs, stairs and walls do not count. At least 16 blocks activate a 32-block radius; the complete frame has 42.
Range grows 16 blocks for every 7 frame blocks: 48 at 21, 64 at 28, 80 at 35 and 96 with all 42. A lit orange iris shows when the frame is complete.
Conduit Power works on players touching water or rain, with the benefits of Water Breathing, Night Vision and Haste (it does not stack with them).
A complete frame attacks one hostile mob at a time within 8 blocks, such as drowned, guardians and elder guardians, for 4 HP magic damage every 2 seconds if the mob touches water or rain.

Java vs Bedrock

Drowned spawn holding a nautilus shell 3% of the time in Java Edition and 8% in Bedrock Edition. In Bedrock Edition zombies converted into drowned count too.

Versions: Describes the current Java and Bedrock releases. See the edition note above for differences.

Frequently asked questions

Where do you find a heart of the sea?

Only in buried treasure chests. A buried treasure map from ocean ruins or shipwrecks marks the spot with a red X.

How big is the conduit range?

The effect has a spherical radius of 32 blocks with 16 frame blocks, 48 with 21, 64 with 28, 80 with 35 and 96 with all 42. Fewer than 16 valid frame blocks do not activate it.

Do conduits work out of water?

Conduit Power only affects players in contact with water or rain, and the conduit must sit in water inside its frame.

Which blocks count for the frame?

Full prismarine, dark prismarine, prismarine bricks and sea lantern blocks in valid frame positions. Prismarine slabs, stairs and walls do not count, and blocks outside the frame positions do not increase its range.