The depth limits — please read

The depth tiers used throughout this archive are real-world diving tiers. They are not invented for narrative effect, and they are not adjustable. If you are reading this guide because you have just arrived from the surface, the following applies to your body, regardless of how you feel about it.

The tiers, briefly

• 0 – 30 m. Recreational. Single-tank air, around an hour of bottom time. Most surface visitors stop here.
• 30 – 60 m. Technical. Mixed gas, decompression mandatory. You will need certification.
• 60 – 100 m. Trimix specialty. Operations, not sightseeing.
• 100 – 300 m. Saturation. Days to weeks of pressurised confinement. Not a tourist depth.
• 300 – 700 m. ADS / saturation specialty. Atmospheric diving suits keep you at one atmosphere. World records hover here. You are not setting one.
• 700 – 6 000 m. Submersibles only. You are inside a pressure hull. The diver never contacts water.
• 6 000 – 11 000 m. Hadal. Crewed DSV expedition only. Rare.

What this means for you

You do not see most of the world below the upper rib unless you commit years to the training. Visitors who attempt to bypass tiers are returned to the surface, if they are recovered at all. There is no waiver that lets you skip decompression. The pressure does not consult your schedule.

The reason this realism is preserved here is simple: the rest of the archive is fiction, and I want the diving not to be. If you wander away from this site curious about real ocean engineering, what you read here will not have lied to you.