When is a cave a cave?

[don Francisco]

While on the surface folks use the terms cave & cavern interchangeably, underwater there's a difference between the two based on depth, distance & light. Most agencies say a cavern becomes a cave at 130' from the nearest point at the surface or when light at the entrance is no longer directly visible, such as around a bend.

If you're asking when a swim-through becomes either, that's a judgement call. My personal rule is that it's a swim through if the exit is clearly visible before entering or if I know that the path to the exit is infallible, such as through a short tunnel with no branches.

Open water divers are trained not to enter any overhead environments, yet we do swim throughs all the time. This unfortunately can lead to danger through what I call exception creep, wherein divers lose sight of the rule after successfully making lots of exceptions. Before you enter any passage decide if it's within your training and is clearly, infallibly, a swim through or if it's a cave or cavern or wreck.

Sadly, most of the specific hazards of penetration diving aren't taught until one takea a penetration course, so it's really a case of what you don't know that'll kill you. (see the NACD sticky at the top of this section)

 

[Papa_Bear]

Some standards allow 200'. It's agency dependent...


Technically, a cave is no longer a cavern once you are out of the day light zone. If you can't see day light from where you are, you are there. However, people can also die in the cavern zone. Any overhead environment presents a higher risk than OW. A silt out can instantly turn a cavern into a cave and prevent you from being able to see your exit. Unless properly trained, don't go into an overhead.

Would you mind citing the Agency that adopted 200ft? I am interested, thank you....

 

[Dive-aholic]

Both cave training agencies - 200 linear feet from the surface.

 

[Gombessa]

Both cave training agencies - 200 linear feet from the surface.

That sounds more like depth, as the mole burrows. Do you mean 200 linear feet from OW?

 

[Dive-aholic]

Isn't the surface OW? Depth is limited to 100'

 

[Papa_Bear]

Witch two? I am NSS-CDS? 130' in or down from Open Water or 130 depth after light loss! IANTD same! NACD same! So witch two do you have or can you post the link to the new recommendations? At least when I was certified!

 

[Blackwood]

Both cave training agencies - 200 linear feet from the surface.

Both?

Is that like both Italian supercar manufacturers: Ferrari, Lamborghini, Maserati, and Pagani?

I assume you mean NSS-CSD and NACD since they're overtly cave training agencies, but there are others. IANTD teaches cave, GUE specializes in cave, etc.

 

[Dive-aholic]

Yes, I meant the cave only training agencies.

I'm away from home right now and don't have either of my manuals in front of me, but when I get back Monday, I'll pull them out and quote them. I don't have the latest of either edition, but they are both the editions just prior to the latest.

 

[InkDiver]

I can only speak for NACD.

From the NACD Cavern/Cave Diver Workbook, page 18,

"3. Penetration distance At this level of training, the diver is limited to two hundred (200) feet of linear penetration from the surface - i.e., back to the unlimited air supply of the surface. If, for instance, the navigable portion of the cavern begins at a depth of sixty (60) feet, the Cavern Diver would be permitted to travel into the overhead environment a distance of one hundred and forty (140) feet. Depth to the navigable entry of the cavern must be subtracted from the maximum linear penetration distance."