Gather 1 Heart of the Sea
Gather 8 Nautilus Shells
Craft a Conduit using 1 Heart of the Sea and 8 Nautilus Shells
Build a frame of Prismarine, Prismarine Bricks, or Dark Prismarine
Place the Conduit in the center of the frame
Use at least 16 blocks for a basic active Conduit
Use up to 42 blocks for full power
Ensure the frame is underwater
Activate the Conduit by completing the frame around it