Conduit

A conduit is a beacon-like block that provides Conduit Power and attacks hostile mobs underwater.

Breaking
$$, conduits drop as an item when broken with any tool or by hand.

$$, conduits drop as an item when broken with any tool or by hand, but a pickaxe is the fastest way to break it.

Conduit power
When activated, conduits give the "Conduit Power" effect to all players in contact with rain or water, within a spherical range of 32-96 blocks. This effect restores oxygen, gives underwater night vision and increases underwater mining speed (slower than above-water mining). Conduits also damage any hostile mobs, like drowned and guardians, within a range of 8 blocks of the conduit. Conduits can be activated in any biome and at any height or depth.

To activate, a conduit needs to be in the center of a 3×3×3 volume of water (source blocks, flowing water, and/or waterlogged blocks), which itself must be enclosed within an activation frame. The frame is built out of blocks in three 5×5 open squares centered on the conduit, one around each axis. Only prismarine, dark prismarine, prismarine bricks, and sea lantern blocks in the frame contribute to activation. A minimum of 16 blocks are required and produce an effective range of 32 blocks. Prismarine-type slabs (including double slabs), stairs, and walls cannot be used to activate the conduit. Any blocks (of any type) that are not part of the activation frame itself but are in the 5×5×5 outer shell likewise have no effect.

The effective radius of the conduit is 16 blocks for every seven blocks in the frame, though the effect does not activate until the minimum of 16 blocks is included in the build. Thus, it extends to 48 at 21 blocks, 64 at 28 blocks, 80 at 35 blocks, and 96 with a complete frame of 42 blocks. A complete frame also carries the additional advantage of attacking hostile mobs within 8 blocks of the conduit by every 2 seconds, if they are in contact with water or rain.

If building a conduit near an Ocean Monument, care must be taken. As said above, the 26 blocks (3^3-1) immediately surrounding the conduit must be water, or the conduit won't work. Initially, you will need at least one block in this volume in order to mount the conduit itself to something (and then remove that block to activate the conduit). When near an Ocean Monument, you may have to remove that block suffering from Mining Fatigue while holding your breath underwater and being attacked by Guardians (which can throw off your "aim" and force you to start mining again). So choose a block with very low Hardness and be sure to use the appropriate tool, preferably one with high Efficiency. With Mining Fatigue, a Dirt block (Hardness 0.5) can be mined by an Efficiency 5 shovel in about 8 seconds; a shovel with no Efficiency takes about 35 seconds. Other possible common choices are Netherrack (0.4 Hardness; needs a pick) or Snow Block (0.2 Hardness; needs a shovel). A Honey Block or Slime Block has 0 hardness and you only need one of them.

Light source
Conduits emit a light level of 15, the brightest light level in the game, whether activated or not; including on land.

ID




Block entity
A conduit has a block entity associated with it that holds additional data about the block.

Trivia

 * When it is activated, the conduit displays the heart of the sea's texture in the center of its model. However, when all 42 blocks have been placed (when the conduit is fully activated) the heart opens like an orange eye.
 * The achievement obtained by activating a conduit refers to the system of whirlpools in Nordland county, Norway.