Welcome to your audio guide for using the Garmin Descent Mk2 during your PADI Open Water Diver training in Monterey, California. If you are training in Monterey, you are learning in one of the most beautiful, yet challenging environments for a beginner. The water is cold, often ranging from 50 to 55 degrees Fahrenheit, and visibility can be limited by nutrient-rich kelp blooms. Your dive computer is a critical tool here, not just for tracking time, but for managing the specific stresses of cold-water diving.
Initial Setup
First, let’s get your watch set up before you even get on the boat or walk into the surf. For your Open Water course, you will be using the "Single Gas" dive mode. To access this, press the top right "Start" button, scroll down to "Single Gas," and select it. You aren't diving yet, so don't press start again just yet. Instead, press the "Down" button on the left to access the settings for this mode.
In Monterey, the cold water increases the risk of decompression sickness because your body off-gasses nitrogen less efficiently when you are cold.
Therefore, it is smart to adjust your conservatism. In the settings menu, look for "Conservatism." The default is usually "Standard" or "Medium," but for a beginner in chilly Monterey waters, we recommend changing this to "High." This makes the algorithm more sensitive, giving you shorter no-decompression limits and keeping you well within safety margins.
Visibility and Control
Next, let’s talk about visibility. Monterey can be dark, especially if you are diving deep in the kelp forests. In the "System" settings under "Backlight," set the mode to "Always On" while diving, or at least ensure it activates at depth. You don’t want to be fumbling to turn on a light to read your depth when you are focusing on buoyancy control.
Also, enable the "Double Tap to Scroll" feature. You will likely be wearing 7-millimeter thick neoprene gloves or drysuit gloves, which make pressing small buttons difficult. With this feature, you can simply firmly tap the face of the watch twice to switch between data screens underwater.
Pre-Dive Procedures
Now, let's simulate the dive day. When you are gearing up, calibrate your compass. The magnetic fields can shift, and since compass navigation is a required PADI skill, you want your digital compass to be accurate. Go to "Sensors and Accessories," select "Compass," and hit "Calibrate." Do this on the shore, away from the metal engine block of a car or dive boat tanks.
As you enter the water, the Descent Mk2 has a surface GPS feature. To mark your entry point—a great way to log your specific dive site like Breakwater or Monastery Beach—hold your wrist above the water surface before you descend. Wait for the ring on the watch face to turn green, indicating a GPS lock. Be careful of kelp draping over your wrist, as it can block the satellite signal.
During the Dive
Once you descend, the watch will automatically switch to dive mode when you pass 1.2 meters, or about 4 feet. Your main screen will show you the essentials: NDL (No Decompression Limit), current depth, and dive time. For your training, your instructor will have you monitor your NDL. In Monterey’s cold water, you might reach your thermal limit before you reach your NDL, but always keep an eye on that number. If it approaches zero, you are running out of time at that depth.
During your ascent, the Descent Mk2 has a variable ascent rate indicator. It will beep and vibrate if you ascend too fast—faster than 30 feet per minute. In the thick training suits you wear in Monterey, expanding air can make you buoyant quickly, so listen for those alerts and slow down if you hear them.
Safety Stop
When you reach 15 feet, the watch will automatically trigger a Safety Stop timer. You will see a countdown for 3 minutes. Hover there, holding onto the kelp if needed to stay stable, until the timer clears.
Surfacing and Logging
Finally, when you surface, keep your wrist out of the water again to catch the GPS exit point. Later, when you sync to the Garmin Dive app, you’ll see your exact path overlaid on a map of the Monterey coastline, a perfect log of your first steps into the underwater world.
Backgrounder Notes
As an expert researcher and library scientist, I have reviewed the article regarding the use of the Garmin Descent Mk2 in Monterey, California. Below are key concepts and facts from the text that would benefit from additional technical or environmental context to enhance a reader’s understanding.
1. PADI Open Water Diver
The Professional Association of Diving Instructors (PADI) Open Water course is the world’s most recognized entry-level scuba certification, covering fundamental physics, physiology, and underwater skills. It qualifies individuals to dive independently with a buddy to a maximum depth of 18 meters (60 feet).
2. Decompression Sickness (DCS)
Often called "the bends," DCS is a condition where dissolved nitrogen, absorbed under pressure, forms physical bubbles in the blood or tissues if a diver ascends too quickly. These bubbles can cause joint pain, neurological impairment, or even paralysis, making the "conservatism" settings on a dive computer a vital safety feature.
3. Nitrogen Off-gassing
Off-gassing is the physiological process where the body releases excess nitrogen through the lungs as ambient pressure decreases during ascent. Environmental factors like cold water can cause peripheral vasoconstriction (narrowed blood vessels), which slows down this process and increases the risk of nitrogen remaining trapped in the body.
4. No Decompression Limit (NDL)
The NDL is a "no-stop" time limit calculated by the dive computer’s algorithm, indicating how long a diver can stay at a specific depth without requiring staged decompression stops. If a diver exceeds this limit, they cannot surface directly and must perform mandatory stops to prevent decompression sickness.
5. Bühlmann ZHL-16C (Dive Algorithm)
While not named in the text, this is the specific mathematical model the Garmin Descent Mk2 uses to calculate nitrogen loading. Adjusting the "conservatism" on the watch modifies the "gradient factors" of this algorithm, essentially creating a larger safety buffer to account for personal or environmental risk factors.
6. Giant Kelp (Macrocystis pyrifera)
The "kelp forests" of Monterey are composed of the fastest-growing organism on earth, which can grow up to two feet per day and reach lengths of 100 feet. While ecologically vital, they can create a "canopy" at the surface that blocks sunlight—creating low-light conditions—and interferes with GPS signals and diver movement.
7. Safety Stop
A safety stop is a recommended pause for 3 minutes at a depth of 5 meters (15 feet) at the end of every dive, even if the NDL was not exceeded. This pause allows for a final period of significant off-gassing before the most dramatic pressure change occurs between 15 feet and the surface.
8. Monastery Beach
Known to locals as "Mortuary Beach," this specific Monterey site is famous for its steep "trench" topography and heavy "sneaker waves" that create a dangerous shore break. It is considered a world-class but highly technical site, which is why the article emphasizes using GPS to track entry and exit points accurately.
9. Neoprene and Buoyancy
Neoprene is a synthetic rubber containing thousands of tiny nitrogen bubbles, which provides insulation but also makes a diver highly buoyant. In the cold water of Monterey, the 7mm thickness required for warmth compresses significantly at depth, leading to rapid changes in buoyancy that the watch's "ascent rate indicator" helps manage.
10. Magnetic Declination
The article mentions calibrating the compass because of shifting magnetic fields; in Monterey, magnetic declination is approximately 13 degrees East. This means "magnetic north" on a compass differs significantly from "true north," making digital calibration essential for accurate underwater navigation.
