Cap of Water Breathing

Wondrous item, uncommon
While wearing this cap underwater, you can speak its command word as an action to create a bubble of air around your head. It allows you to breathe normally underwater. This bubble stays with you until you speak the command word again, the cap is removed, or you are no longer underwater.
Dungeon Master´s Guide
  1. DnD 5e Magic Items › Cap of Water Breathing