Depth, Air & Time
How Long Can You Stay Underwater?
Two limits decide your dive time: how much air you have, and how much nitrogen your body can absorb.
Your dive time is set by whichever runs out first: your air or your no-decompression limit (NDL). On a typical recreational dive that's around 45–60 minutes. In the shallows, air usually limits you; at depth, your NDL does.
- Typical dive
- 45–60 min
- Shallow limit
- Usually air
- Deep limit
- Usually NDL
- Reserve
- Surface by 50 bar
The two limits on every dive
How long you can stay down comes down to two things working against each other:
- Your air supply — how much gas you carry and how fast you breathe it. This depends on tank size, depth, your SAC rate, activity and stress.
- Your no-decompression limit (NDL) — the maximum time you can stay at a given depth before you'd need mandatory decompression stops on the way up. The deeper you go, the shorter your NDL.
Whichever limit you reach first ends the dive. Smart planning keeps both comfortably in reserve.
Roughly how long at each depth
| Depth | Approx. NDL (first dive) | What usually limits you |
|---|---|---|
| 10 m / 33 ft | Very long (hours) | Air |
| 18 m / 60 ft | ~56 min | Air or NDL |
| 30 m / 100 ft | ~20 min | NDL |
| 40 m / 130 ft | ~9 min | NDL |
NDL values vary by dive computer and algorithm and shorten on repetitive dives. Treat the figures above as ballpark, and always follow your computer or tables.
How to extend your time underwater
- Dive shallower — by far the biggest lever for both air and NDL.
- Breathe slowly and stay relaxed to lower your SAC rate.
- Nail your buoyancy and trim so you're not wasting energy or gas.
- Use the right tank size for your air consumption.
Know your limits with the NDL & Gas tools
Diving Standard's No-Stop Time (NDL) and Gas & SAC planners show exactly how long you can safely stay down — plus free lessons to master the theory.
Get the Diving Standard appFrequently asked questions
What limits how long you can scuba dive?
Either your air supply or your no-decompression limit (NDL) — whichever you reach first. Shallow dives are usually limited by air; deep dives by NDL.
How long is a typical recreational dive?
About 45–60 minutes. Shallow dives can last well over an hour; deep dives may be only 20–30 minutes because of faster air use and shorter NDLs.
What is a no-decompression limit?
The maximum time you can stay at a given depth and still ascend directly (with a safety stop) without mandatory decompression stops. It gets shorter the deeper you go.