No-Decompression Limits, Explained Simply

Every time you dive, your body soaks up extra nitrogen from the air you breathe. The deeper you go and the longer you stay, the more you absorb. A no-decompression limit (NDL) is simply the maximum time you can spend at a given depth and still swim straight to the surface (at a slow, safe rate) without needing mandatory decompression stops.

Think of it like a sponge

Your body tissues act like sponges. At depth, the higher pressure pushes nitrogen into them. When you come up, that nitrogen needs to come back out slowly through your lungs. Ascend too fast, or stay down too long, and it can come out of solution as bubbles — that's decompression sickness (DCS), also called “the bends.”

Deeper = shorter

Because pressure increases with depth, nitrogen loads faster the deeper you are. That's why your NDL might be over an hour at 40 feet but only around 20 minutes at 100 feet on air. Exact numbers vary by table or computer algorithm, so always follow your own computer or dive plan.

Repetitive dives

Nitrogen doesn't disappear the moment you surface. On our two- and three-tank charters, you start your second dive already carrying some leftover nitrogen, so your NDL will be shorter than it was on dive one. That's normal — your dive computer tracks it for you, and the surface interval between dives lets your body off-gas.

How to stay well inside your limits

• Do your deepest dive first, then progressively shallower dives.
• Ascend slowly — no faster than 30 feet per minute (your computer will warn you).
• Make a 3-minute safety stop at about 15 feet on every dive, even when it isn't required.
• Don't dive right up to the limit. Leave a buffer, especially on repetitive days.
• Stay hydrated, rest well, and avoid hard exertion right after diving.
• Wait at least 12–18 hours (longer after multiple days of diving) before flying.
• Consider Nitrox — breathing less nitrogen means longer NDLs at typical recreational depths.