Category Archives: In the Water

Do: Open Water Descent and the Visible Spectrum

Getting briefed on the first dive on Saturday morning. 7 ml wetsuits, hoods, booties and gloves are worn by students.

Getting briefed on the first dive on Saturday morning. 7 ml wetsuits, hoods, booties and gloves are worn by students.

In the grey-blue waters of the Pacific Northwest not far from the horns of the Washington State Ferry and comfortably surrounded by the piers of the Mukilteo T-Dock I’m starting my first open water dive. I’ve heard, through the rumor mill and from seasoned veterans, that the waters off my coastal home are sought after by divers the world over so I’m curious to do my own exploration. I’m bundled cozy in a 7 mm wetsuit, gloves, hood and booties. Other divers, most instructors, layer fleece under dry suits, donning elaborate systems of lights and air tubes in the parking lot beneath the Silver Cloud Inn. The water temperature sits in the mid 50s and the outside air rises to the low 70s as the day progresses, hindered only by a brisk breeze.

This dive, one of four toward completing my open water certification over the next two days (two dives to 30+ feet Saturday and two to 60 feet Sunday), has evolved into a nonreference descent. My ears refused to equalize at 15 feet, so I abandoned the first attempt and returned to the surface with my instructor. On the second attempt we head straight down and it’s a little disconcerting sinking slowly, directly to the bottom, but certainly a trip to experience the full vertical transition. Until we reach the bottom the visibility is limited to about six feet – the span of my arms – making me aware of how much I’m not aware of how far the bottom is from the tips of my fins. So I settle in, letting small amounts of air from my BCD and equalizing my ears.

At depths past 30 feet the world takes on a green glow. Note the neon yellow fins and neon orange whistle against my shoulder. (Photo courtesy: John Sanders, DiveZen Scuba)

At depths past 30 feet the world takes on a green glow. Note the neon yellow fins and neon orange whistle against my shoulder. (Photo courtesy: John Sanders, DiveZen Scuba)

Just below the surface the view in front of my goggles cancels into a fray of broken green and red algae bits that keep rhythm with the wind and wake. Around 10 feet surface sounds retreat, the water begins to calm and a vibrant green glow sets in from above.

Light after 15 Feet

Water is a selective filter of color and as we sink I watch the saturated red on my instructor’s dry suit fade to a dull, murky green. The color becomes indistinguishable from the surrounding environment at 15 feet. Part of the glow I’m now enmeshed in is due to the organic matter in the waters of the Pacific Northwest but another part is due to the properties of light as it reaches below the surface. A little science review before we head farther down: Imagine a tank of clear water 200 feet deep. If we were to suspend a white light above the tank and descend with six colored blocks – each a color from ROYGBV – the water would filter the colors one by one as we dropped deeper into the tank and further from the light.

Water acts as a selective color filter, absorbing light as depth or distance from the source increases. (Graphic courtesy of:

Water acts as a selective color filter, absorbing light as depth or distance from the source increases. At a depth of 60 feet, only 18 percent of light rays penetrate and only one percent reach a depth of 330 feet. (Graphic courtesy of: University of Maryland Space Systems Laboratory)

The loss of color extends sequentially through the light spectrum – like my instructor’s suit, the red block would be the first to lose color followed by orange then yellow – until, after about 75 feet the last block to lose its hue would be violet. Interestingly, some species of clear jellyfish have a red stomach. Since red is the first color to disappear in the visible spectrum under water, the red (or lack thereof) hides the jelly’s last meal.

If you ever wonder why neons tend to be ubiquitous in water activities, here’s your answer: Ultraviolet, invisible to humans and found after violet at the end of the light spectrum, can travel to extreme depths. When a neon color is struck by invisible ultraviolet, it will glow or fluoresce which is why alternate air sources and other items needing ready accessibility are commonly created in neon.
In our subsequent dives the haze began to clear at a depth of about 30 feet and visibility increased to a distance of nearly 25 feet along the bottom, remaining steady as we descended to 60 feet. Green, blue and violet remained and our instructors used their lights to reveal the nuances of the undersea creatures: Brown mottled flatfish, orange penpoint gunnels, kelp greenlings protecting eggs and dungeness crab (all documented by our class) navigate the sand and pebble-covered bottom, relatively unaware of our presence. And if you look closely, sea stars no larger than the nail of my little finger hide between the pebbles beneath the feet of hermit crabs. At this particular location a large geodome made of PVC pipe has been constructed at 50 feet and become host to a number of small invertebrates including copper rockfish. A short distance away the instructors gently pried apart a set of submerged tires treating us to the rare sight of the resident octopus curled in his den.
Even with the understanding of water’s color selective filtering, I wasn’t expecting the green hue. I admit I’m not really sure what I was expecting – maybe a soft, blue-grey-magenta to match the sunrise or a grey-blue flannel hue to match the morning sheen of the Olympic mountain range. I’ve taken a liking to surfing these waters and grown used to the looks of surprise when I mention it. And I can say honestly that what’s on the bottom is well matched to what we experience on the surface of our Emerald City. Green is the color du jour. It’s dark, it’s sometimes tempestuous but when you stop and look just a little deeper, shapes and then colors are revealed that leave you glad you buttoned up and stepped outside.

As we head back toward shore I’m handed a weightless, bloated object puffed to the size of a football: A sea cucumber, red by a nearby dive light and marked by small yellow nodes. I carry it a short distance and its name dawns on me: hoi sam. The Cantonese translation to “happiness”.

How to get there: Mukilteo T-Dock

The entry to the diving area is found next to the Silver Cloud Inn in Mukilteo, close to the ferry terminal. From I-5, take exit 189 and merge onto WA-526 toward the Mukilteo Ferry Dock.

Follow the signs all the way to the ferry dock – 526 becomes 84th St and you’ll have to take a right to stay on it after the Boeing field, then a right onto 525 – until you get to the waterfront. Take a right on Front Street (directly in front of the ferry terminal). Head 2 blocks and park next to the Silver Cloud Inn (at the intersection of Front St and Park Ave).

View map


Complete Diving Manual by Jack Jackson > Overview of Mukilteo T-Dock
Pacific Northwest Scuba > Mukilteo T-Dock

Do: Diving: Confined

The first few nights of instruction were held in the pool at Underwater Sports Seattle. (Photo courtesy: John Sanders)

The first few nights of instruction were held in the pool at Underwater Sports Seattle. Duncan heads into Snell's window. (Photo courtesy: John Sanders, DiveZen Scuba)

There are four of us. We’ve spent the past five minutes floating at eye level. The sweet spot. Where we’re neutrally buoyant between the weights strapped to our waists, our own natural propensity for displacement and the air in our BCDs. The point where we’re expending the least amount of energy. We’re watching our instructor spin clockwise on a lateral axis – he’s unbuckled his weight belt and is demonstrating the technique for replacement. A few key things to pay attention to here: one, he’s holding the belt in his right fist; two, the buckle end dangles somewhere near his ankle; and three, he begins the roll face down. Combined, all of these steps ensure once his roll is complete his weight belt will be resting on top of him 360 degrees later. This also guarantees he’ll thread the right end through the buckle on the left, leaving his belt in the standard pull-right release. Simple. Problem is, I naturally roll counter-clockwise.

I really roll counter-clockwise.

And even though I’ve hooked my right thumb into the D-ring on my BCD to drop my right side, it only serves to lock me there, dangling my allotted 10 lbs, unable to flip over onto my air tank and complete the roll. It’s awkward, but eventually I get it. With a few haphazard kicks and shoulder thrusts and a few more wriggling attempts I find the right propulsion to execute the move repeatedly in increasingly more graceful swoops and it gets added to the growing list of skill scenarios we’ve played out in the 12 foot confines of four pool walls.

Deep Breathing: Going beyond the 12 feet we've adjusted to in the pool it will be even more important to breathe and breathe well. At sea level 14.7 pounds per square inch (psi) of pressure (or one atmosphere) is pushing down on our bodies. As we dive, for every 33 feet we descend, one more atmosphere is added. At 66 feet, the pressure equals 44.1 psi and at 99 feet the pressure equals 58.8 psi - at this depth the lung volume of a diver is one quarter the volume at the surface. To travel into this high-pressure environment we have to make some adjustments. The regulator from which you pull air keeps the pressure within your lungs equal to the pressure of the surrounding water via a two-stage device: The first (attached directly to your tank) reduces the pressure of the air compressed in your tank to about 150 pounds per square inch (psi) more than the surrounding water pressure. The second (the mouthpiece from which you breathe) further reduces the pressure to match the surrounding water and make it comfortable for a diver to inhale. Using this system for breathing and other precautions, including staying warm, we humans can safely descend three or four atmospheres.The regulator from which you pull air keeps the pressure within your lungs equal to the pressure of the surrounding water via a two-stage device. (Photo courtesy:

Now on to releasing my BCD and climbing on top of it, still weighted, careful not to lose contact lest I go plummeting to the bottom without air. I have to raise both hands and show my instructor I’m securely astride the tank.

Gaining Comfort

I make it out to be more tedious than it really is. Truthfully I’ve been loathe to leave the pool these past four nights. Climbing out sometime close to midnight after hours spent gaining comfort with a series of skills required to master Open Water Dive certification. I donned the BCD the first night, inserted my regulator and timed my first intake of breath to my slide beneath the surface. Each subsequent descent and each night following has eased the pressure in my ears – at first requiring prolonged stops every foot to pinch, blow, grind jaw, frown by the last class I easily slip from the surface to bottom with barely a flex of my throat muscles. This is good because come Saturday I’ll be traveling five times deeper.

I’ve passed my written exam and now, come Saturday, in the 55-degree open waters near Mukilteo, Wash., I’ll be demonstrating at a depth of 60 feet my mastery of the 20-some skills I’ve become comfortable with at 12 feet: The flooding and/or loss of my face mask; the loss and retrieval of a regulator; the loss of air and safety ascent procedures; manual calculation of dive tables; hand signals and so on and yes, removing and replacing my weight belt and BCD. The most rewarding skill Ive learned is the ability to exert subtle, micro-control over ascent and descent by varying the amount of air in my lungs. Eventually, I’m told, this becomes second nature and integrates seamlessly into a regular breathing pattern. I’m almost there but new focus will be required against the currents of the Pacific Ocean.

We all know comfort breathes familiarity. And familiarity can mean the difference between something magical and an open invitation to disaster. Repetitive practice and mastery of these skills keeps them ready for retrieval, drifting in the back burners of our minds, allowing us to commence with firing the imagination and sinking into the upcoming view below.

Do: Dive On

dive_flagGetting my dive certification has been ever present on my list of adventure goals. Probably somewhere down near #5 (put there about the time I saw the intro credits to Thunderball). So when a friend mentioned Underwater Sports in Seattle was hosting their annual dive fair complete with steep discounts for certification and gear, I couldn’t resist.

Diving, I’m realizing, is an expensive hobby – I had an inkling but didn’t fathom the complete extent – but it’s also evolved to be considerably more practical and achievable than history has provided. The cut, hollow reeds of ancient swimmers are the first documented examples of rudimentary snorkels. Soon these were combined with eye goggles fashioned from thinly sliced and polished shells of tortoises – popular with Persian divers in the 1300s. A few hundred years passed and with the invention of the air pump by British engineer John Smeaton in the late 1700s diving took on a whole new meaning – surface collaborators now had the ability to pump air to divers. And then came the coup de grace (not literally) when subsequent English and French inventions perfected the closed-circuit oxygen rebreather and Cousteau released his notorious Aqua-Lung in 1943. Now more commonly referred to as scuba (self-contained underwater breathing apparatus), the invention officially cut the air-filled umbilical cord between diver and surface.

Walk into any dive shop now and you have a plethora of options to experience the deep frontier. I don’t intend to get into details here but I’ll note that the sales people and instructors in attendance all rested on two pieces of advice: You get what you pay for and it all comes down to what feels the most comfortable to you. Hmm.

For training the dive shop supplies the wet or dry suit (needed for both pool and open water activities), regulator, air tank and BCD (bouyancy compensator device – an inflatable vest that attaches the air tank to you). I come pre-equipped with booties and gloves – procured for surfing in the Pacific Northwest – so all I needed was mask, snorkel and fins.

I selected a frameless mask and an SV1 snorkel (both Atomic Aquatics): The frameless mask means I don’t get annoyed by a dark ring interrupting the periphery of my vision and its low volume means if it gets bumped and filled with water, I have less to clear. The snorkel’s tube hosts an internal scupper valve which allows water to pass through the snorkel without collecting at the bottom of the breathing passage. The tiniest burst of air clears my mouthpiece. It also features a quick disconnect and sliding snorkel keeper – a small thing but a fixed snorkel was my biggest complaint in Hawaii. I’m still in the market for flippers so I’ve borrowed a friend’s. I’m debating about the merits of split fin vs. solid and a variety of buckle styles so I’m content to use hers and a set from the dive shop for a bit.

Choosing to acquire dive certification on your home turf gives you a couple of different options for scheduling, initial cert and continuing education.  When I’m finished (yes, I have my fingers crossed) I’ll be considered a PADI Open Water Diver and certified to dive up to 60 feet independently (without the supervision of a divemaster – required if you receive only PADI Scuba Diver cert, typical when you get certified on vacation).  This also means I’m doing no-decompression diving – safety stops aren’t required and I can go straight to the surface at any point without risk of decompression sickness (the bends). After full cert I can choose to pursue specialties and/or continue to Advanced Open Water cert and then Enriched Air (deep open water dive) cert. With practice and over time I’ll be ready to dive to 100 feet and then to the 130 feet mark. Depths beyond this are reserved for technical or commercial diving. View the PADI course levels.

Rather than bombard myself with a weekend intensive, I’m spreading my coursework out over two weeks. Two days of open water diving at Mukilteo, Wash. will be the icing on four nights of pool time (confined water dives). During the course I’ll be responsible for in depth review of a 260+ page instruction book, learning to read dive charts and do the calculations even under stress and learn to stay calm when a panic situation arises. I’m taking the course by myself so my instructor will assign me a buddy and we’ll be responsible for each other throughout the course.

Though it’s been on my list for years, aquiring my certification is a uniquely sensitive goal for me. Shortly after graduating I learned a college friend drowned while diving on vacation. I wasn’t particularly close with her but we ran in the same circles and had spent some time together. Dena was recovering from the flu and panicked underwater – either from feeling ill or being disoriented. And though I’ve been told multiple times that it’s never safe to dive while ill or recovering and I don’t intend to do so, it’s still a lingering thought in the back of my mind – as these things are and should be – and a primary reason for my delay in getting certified. But, like I said, sometimes these opportunities come along that you can’t refuse and here I am: registered, gear acquired and ready to pursue another means to adventure.

Getting Certified:

Professional Association of Diving Instructors (PADI) – The world’s leading scuba diving training organization, PADI provides a diver education system, access to equipment, environmental conservation initiatives and opportunities to experience diving. | Locate a PADI dive shop

Seattle & adjacent cities:

Underwater Sports
Seattle Scuba School
Sound Dive Center

Insurance, Safety & Emergencies:

Diver’s Alert Network (DAN) – As a nonprofit, DAN exists to provide expert information and advice for the benefit of the diving public. DAN’s primary function is to provide emergency medical advice and assistance for underwater diving injuries, work to prevent injuries and promote diving safety. DAN promotes and supports underwater diving research and education particularly as it relates to the improvement of diving safety, medical treatment and first aid. And DAN provides accurate, up-to-date and unbiased information on issues of common concern to the diving public, primarily, but not exclusively, for diving safety. |

The DAN Student Membership Program is free to all entry-level divers. When you enroll to become a student member, you’ll receive these benefits, including up to $20,000 recompression treatment insurance. It’s unlikely you’ll ever need to use it but, if you did…

DAN America membership and dive accident insurance are available to residents of the United States, Canada, Mexico, and 44 other countries in Central and South America and the Caribbean.


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