Air Safe

This airtight 1-foot diameter metallic sphere is able to withstand pressures of up to 15,000 feet without rupture or collapse. While you are at a depth of 5,000 feet or less, you can use a bonus action to press the air safe’s valve against your mouth and breathe from it. When at a depth between 5,001 feet and 11,000 feet, breathing from the air safe requires an action. Between depths of 11,001 and 15,000 feet the air safe’s valve only functions with a DC 13 Strength check and a DC 12 Dexterity check is needed to successfully breathe from it.

Most air safes only carry enough air for a single Medium-sized creature, but their design makes them only function a single time before needing to be brought to the surface to be refilled.