View Full Version : Scuba diving

05-04-2016, 11:10 PM
I need to write a scene in which two MCs go scuba diving to explore an underwater structure. Problem is, I've never dived, and I'm not likely to do so. :) Can anyone refer me to any online resources or books that describe what the "lived experience" of scuba diving is like? I know the technical stuff that's involved. I just don't know what it FEELS like. Or sounds like, or any other sensation that isn't obvious from watching underwater video.

(If it matters, one MC is twelve years old.)

Thanks in advance!

05-08-2016, 11:30 AM
I'm not a scuba diver, but I do have a couple in the family. If you can't dive yourself I'd suggest you try to find an old video game, Everblue 2 for the PS2, which was written by Arika, a group of scuba-diving coders. They also did Endless Ocean 1 and 2 for the Wii, but those are often played third-person and 2 has dinosaurs. The games aren't perfect simulations because you can expect music effects etc. but they are as accurate as the coders could make them with allowances for gameplay. According to the divers I know, the Arika games are very close to accurate in terms of feel.

05-08-2016, 06:27 PM
Try PADI for references: https://www.padi.com/scuba-diving/padi-courses/course-catalog/try-scuba-diving/

Hit a local dive shop and see if they have divers you can interview. Or drop an email to any dive shop and ask.


Mark G
05-11-2016, 10:01 AM
I'm a certified scuba diver. Wreck diving is some of the most complex diving, due to the typical depth and the danger of getting stuck or losing your way. I haven't dived in a "dry suit", only wet suit. Unless you're in the tropics, temperature is a big factor because you only have a thin layer of neoprene (and water that's leaked in and warmed by your body) between you and stuff trying to suck the warmth out of you. A dry suit is better for keeping you warm by keeping the water out.

Every 33 feet down changes the pressure around you by 1 atmosphere. That mostly hits you in the ears, so you have to "equalize" a lot (hold your nose and make a swallowing motion with your throat), so you don't blow your ear drums out. Think about how your ears pop when driving up/down hills, times 10. Diving while congested is not recommended.

So far, you have 1. it's cold, and 2. it's a quick pressure change.

Next, you're on limited air. Normal air will last a very short time, less than an hour, and the more you breathe the less time you get. So divers practice breathing "even" and not too deep and not too shallow. You can get special mixes of air to last longer, or use a "rebreather" (basically a scrubber that pulls apart carbon dioxide and makes oxygen as long as the toxic chemicals last that make that happen) - those can last a looooong time. But you have to monitor your oxygen level because it can get too high and intoxicate you. Good luck coming up after that...

Every minute you're at more than 1 atmosphere, your body is storing Nitrogen in your blood stream. It has to go someplace, after all. So as you're coming up from the depths, it's crucial to come up slow so you can "off-gas" (get the Nitrogen out of your blood). Otherwise, you can get lethal and/or very painful bubbles popping up all over. This is called "the bends".

All that stuff is why people go through a few weeks of training to get certified.

Katharine Tree
05-11-2016, 06:58 PM
I'm also a certified diver. Happy to answer questions via PM, if you like.

-It's very awkward to walk in fins. You do it backward so you don't trip on them. If you have to fall any distance to get to the water--basically if you're doing anything but walking in--you go backward so you don't dislodge your mask

-Wetsuits are super hot if you aren't in the water. You wear a swimsuit under them, unzip the top, and let it hang around your waist until you're ready to dive

-The immediate sensation of getting in the water is that it's nice and cool. Being in the water is just like being in the water, except you're frrreeeeee! You can go as deep as you want! And you don't have to worry about falling, which is the best feeling. You can just hover in front of a dropoff, slowly going down and examining things on the way, like watching television

-Animals are friendlier than you'd think. Schools of fish will adopt you as one of their own. Cuttlefish are skittish. Barracuda will follow you like a dog

-Colors fade out, the deeper you get. Red goes away first. You can still see it fairly well around 60 feet, which is where the best coral is, if your people are diving near reefs. By 90 feet you only see yellow and blue

-There's a pretty steep thermocline below 90 feet. Water gets cold and dark fast. At 120, your dive computer is ticking away a minute of dive time every second. At 150, unless you're breathing Nitrox, you are getting narked and can't think clearly. You need a rope to ascend from that deep--otherwise you're too likely to get confused and never figure out which direction is up.

-You ascend no faster than a foot per second, to avoid getting the bends

-Oh, one more important thing: your dive computer. You wear it on your wrist and it keeps perpetual track of how much dive time you can afford. As I said above, this changes depending on what depth you've been to and how long you've spent there. Typical reef diving, between 60 and 90 feet, you can do about four one-hour, one-tank dives in a day (two in the morning, a break to off-gas, two in the afternoon). Any deeper than that and you're looking at a lot less time.

-One MORE thing: it's important to get the saltwater off your gear as soon as you're done diving. Most divers bring jugs of fresh water along to do this. People with long hair do well to bring a bottle of spray-on conditioner and a hairbrush, too

05-11-2016, 07:29 PM
I went scuba diving once in Bermuda. Did a basic 30-45 minute prep and off we went. What I remember is the ear popping, the sound of my breathing through the respirator (it reminded me of the old Magnum P.I. show and the sound effects whenever he went diving) and the basic hand signals.... "okay" and "shark". lol The other thing is it's very hard to be dexterous in the water. My weight belt loosened and I had a hell of a time getting it cinched tight again. As a matter of fact, I think the professional diver we were with ended up having to do it because my fingers were all fumbly. We went down about 40 feet and the view looking up was amazing. Last thing, those air tanks are surprisingly heavy.

05-11-2016, 10:39 PM
What's a wet suit? :)

Okay, I'm in Florida. Here you often only need a swimsuit and that's not even "needed." What you need will change on where the dive and structure are located, what the structure is and what the diver is doing. You can change equipment to meet the story needs, rebreathers, Nitrox diving mixes and so on. I've dived (and free dived) structures that are only 10 feet below the surface to the top, intact buildings missing doors and windows. Far less difficult than a wreck dive at 200 feet in zero visibility and swift currents. Commercial divers rarely get to work on sunny, tropical reefs inhabited by pretty fish and girls in grass skirts.

The main thing I can add that may aid your story is the disorientation that occurs. We have a lot of divers down here that get into trouble because the dive starts at 30 feet but the slope of the reef takes the diver to 120 feet or deeper without them realizing it. Low on air at 30 feet isn't a big issue. At 150 feet it's a major issue. Seems to be where the majority of recreational diving injuries and deaths come from.

Here in Florida, we have six of the seven man eating sharks as natives and the seventh as migratory. But the idiots that get bit are often spear fishing and keeping their catch hanging off their waist. Diving the cuts in the Keys, where water passes from Gulf to Atlantic, you see a ton of predatory sharks waiting for the fish that pass through with the tide. But none of them seem to care about humans as dinner.

Diving is fun, generally safe and, unfortunately, addictive. :)


05-16-2016, 05:37 PM
Thanks so much, everyone! This is very helpful.

I had always wondered why divers go backwards off of a boat. Now I know! And the thing about fading red colors is good to remember, as it will affect one scene materially.

In the two scuba-diving scenes I'm writing (now two, not one), the water is still fairly cold, and definitely not tropical. One takes place off of Virginia Beach in late summer, so I'm guessing a wetsuit would be fine? The other is off of Cape Cod in March -- definitely drysuit territory. :) But they don't dive deeply in either case. I'll make sure the characters stay underwater less than an hour.

Katharine Tree
05-16-2016, 07:02 PM
Sounds right. Wetsuits are measured in millimeters of thickness. The more mms, the warmer it is. Diving in tropical waters you can get away with only a swimsuit if you stay quite near the surface; down around 60-90 feet it's better to wear a "skin," or a wetsuit of 1-1.5 mm.

I did my qualifying dives in an Illinois quarry in September. For that we wore 6mm "Farmer Johns" and jackets. Two-piece wetsuits, basically.

05-20-2016, 03:51 PM
If wearing a drysuit, that brings a whole new element to the experience. It will have a waterproof zip, very unlike a normal zip, often across the back of the shoulders so once you've climbed in and got your head & hands through the neck and wrist seals, it needs someone else to zip you shut. (Some suits have front mounted zips running diagonally across the body so you can do them yourself, but the zip has to be longer and as it's viewed as a weak spot people often prefer the simpler design.)

The suit is subject to pressure as you descend exactly like your ears. If the suit doesn't get its internal pressure equalised it will squeeze and pinch very strongly. I've seen big bruises on people who didn't pressurise their suit as they were descending. So the suit has its own air hose, just to fill it with gas. It comes off the main regulator exactly like the air feed to your buoyancy device (BCD jacket or wing or whatever). It goes in on the chest and you have to press a button to let air in. That air then has to come out as you ascend; there's often a one-way valve on the wrist, so simply raising your arm allows excess air to escape. While the air is in the suit it provides buoyancy - the suit itself is therefore a secondary buoyancy control device working alongside your BCD.

Regarding those neck and wrist seals -- they have to be tight but not too tight. A new suit will need to have them trimmed to fit your own needs. I've seen people travel all the way to a dive site only to abandon their days diving because a new suit was strangling them and they hadn't thought to adjust it.

Pitfalls of a drysuit -- if the air inside it flows to the legs you can end up ascending feet first without intending to. This is serious -- any uncontrolled ascent is bad news, and there's no pressure release on the feet or legs. A marine archaeologist here in the UK died on a solo dive with inflated legs and his head underwater -- he didn't have the strength to fight the buoyancy and get right-way-up. My drysuit training included a practice of this scenario (in a safe pool setting) to learn to "tuck under" and push inflated feet and legs back under the water.

Another nuance -- some divers who do a lot of cold water work have a separate gas cylinder for the drysuit containing another gas, like argon, which insulates better than air. This is yet another level of complexity though.

Other general "experience" stuff covering the five senses. People have described already what you'll see and hear -- sounds are mainly whooshy bubbly noises, everything very distorted. Though you hear boats going over as a distant roaring sound from the engine. You'll feel the pressure, and the cold / warmth, and feeling weightless like you're floating in space is a big deal. If you get nitrogen narcosis at depth (30m is where is often kicks in) you'll feel disoriented, and it can feel as if you're not moving even when you kick hard, or you're swimming through treacle (especially in low visibility). As for taste and smell, diving equipment is all plastic and rubber and neoprene - expect vaguely chemical smells and tastes, especially with new kit which was boxed up as soon as it was manufactured. The brand I bought put a kind of vanilla fragrance in their stuff to mask the other smells. The air from a scuba regulator is very dry as well, that's another thing, because it has to be pressurised in steel cylinders without causing corrosion. And it is cold too -- compressed gasses cool down when they expand. So your characters will have very dry mouths when they finish.

That's all I can think of for now...

05-20-2016, 05:38 PM
I had no idea drysuits were so complicated. And they require extra training, too? Hmm. I'm going to have to rethink this Cape Cod scene -- it would be nice if the characters could get away with just wetsuits, to avoid all this craziness, but that's probably not realistic. Am I right in guessing that drysuits pretty much have to be custom-made to an individual? It sounds like a close fit is really important for it to function correctly.

Thank you for the sensory descriptions, too. Good stuff.

05-21-2016, 01:47 AM
They don't necessarily have to be custom made, but most people go down that route unless they find an off the peg one that fits really well (and just like in a clothes shop, if you try it on in the changing room and it looks and feels comfortable, that's good enough). The close fit isn't such a big deal - having a bit of room in there helps you move, and the air you pump in or release will determine how "tight" it feels once you're underwater. (It's not stretchy by the way; the material is like very heavy cloth or fabric coated to make it waterproof.)

There is a possible alternative, something called a "semi dry", made of thick neoprene like a wetsuit which is designed to let in water but it's a tight fit so the same water is next to your skin the whole time. I.e once it gets up to body heat it stays at that temperature, and there's no flow of water in or out so you don't get cold water flowing in from outside every time you move. I wore one during early dive training (getting used to the basics when drysuit training was still ahead of me) and on one occasion was in water at 4 degrees C (4C above freezing, 39F). It felt bitterly cold, and we ended early when it got too much for one of the others (I would have called it if someone else hadn't) but in theory you can get that close to freezing point wearing one so a few degrees warmer should be okay if the divers are fit and healthy and have somewhere warm and dry to go to once it's over.