Game Modes
Subnautica currently features four different Game Modes.
Freedom Mode
Oxygen and health are the only resources you need to manage to stay alive. Energy is consumed by all electric tools, including the Cyclops, Seabases, and the Escape Pod.
Survival Mode
Similar to Freedom mode with the addition of needing to maintain your food and water (H2O) levels as well as oxygen and health. If your health reaches zero percent (or you drown), you may lose some or all of the items in your inventory that were collected without first securing them by going into your Escape Pod, Seabase, or Cyclops.
Hardcore Mode
In addition to the food, water, oxygen, and health requirements of Survival mode, Hardcore mode goes one step further by adding one life; if your health reaches zero percent, your game ends, forcing you to completely start over from the beginning. In addition to this, Hardcore Mode does not warn you when you have low levels of oxygen, food, or water.
Creative Mode
In Creative mode player death is disabled, materials and Blueprints are not required for crafting, vehicles have no energy requirements and cannot be damaged, and the story is disabled. This mode is currently only available in Experimental Mode.