They can craft a Conduit using Nautilus shells and a Heart of the sea. A Conduit needs at least one ring of Prismarine block to activate. Like the beacon, the more rings the Conduit is surrounded by, ...

A conduit can be one of the most useful items in Minecraft. When fully powered, it grants water breathing, haste and night vision. This is only in effect when underwater or in the rain, but is ...