How long can you stay underwater on SCUBA?

The final question everyone asks.   Unfortunately, there is no short answer to this question, and the usual response is: it all depends.  After the strange looks, I start to explain some physics and physiology, and lose most people after a few sentences.

Let’s start out by changing the question.  Why do you get out of the water?  Without getting too deep into the physics / physiology and finances, we have one of several reasons:
1)   Limited ability to withstand the temperature drain of water immersion
2)   Limits on the amount of gas we have
3)   Large fish with teeth

Normally, 1 and 2 are the major limiting factors.  When the original question is posed, it is usually referring to our gas limits, so let’s look closer at the factors affecting it.

Without getting too deep into the explanation, lets just use a couple of generalizations.
1)  The deeper you go, the less time you have.
2)   The harder you work (underwater) the less time you have.
3)   Different people consume air at different rates.
4)   The bigger you are, the less time you will have.
5)   New divers will have less time than experienced divers.

Numbers 1 and 2 are immutable facts.  Numbers 3 – 5 are generalizations that vary greatly based on the individual, their physical fitness, and level of skill and comfort in the water.

Just to throw a wrench into the works, we must also consider the size of the tank.   As discussed before, different tanks carry different amounts of gas, and can allow us to stay longer.

Let’s consider an average dive (not working hard), by an average diver at an average depth (60 ft) with the average tank (Aluminum 80).  In general this diver should have gas to dive for about an  hour.

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5 Responses to “How long can you stay underwater on SCUBA?”

  1. Sydney says:

    heyy, i was wondering, when was the last time you updated your site?? i need to know for a project

  2. Dave Oldham says:

    I try to get an update in every week or two. It’s tough when we get busy diving in the summer.

  3. [...] gas in the diver’s tanks, and the no decompression limit for the depth.   There is a detailed explanation of the factors involved, but an average diver can stay between 60-80 ft for about an [...]

  4. bob says:

    how long can you stay under water with a average tank.

  5. admin says:

    Bob,

    On average a new diver can spend about 40 minutes at 60 ft on an average tank.

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