Pressure

When a player goes too deep down an ocean or down underground, or too high into the sky, they will suffocate slowly because of pressure. The only way to counter this is by wearing reinforced armour. Each piece of reinforced armour only slightly diminshes the effects of pressure, while a full set can completely negate it. Reinforced armour can be crafted by combining a piece of armour with the a piece of the same material it is made of, on a smithing table. Reinforced armour also gives the player more protection. A player can also wear a mixed set of reinforced armour of different materials, like gold helmet, iron chestplate and leggings and diamond boots.