Scuba Diving 101
August 25, 2022
Scuba diving offers an incredible opportunity to explore remote regions of our planet, study fascinating wildlife and experience new adventures. But it’s easy to feel intimidated by all the new gear and techniques you’ll need to learn. A dive computer is an essential piece of a diver’s equipment, providing essential information such as depth, dive time and decompression. Learning to set up and use your dive computer can also seem daunting, but the Garmin Descent™ Computer Series, which also function as smartwatches, simplify things both above and below the surface. It all starts with identifying the type of dive you plan to do – from there you adjust a few settings and jump into the water. Let’s discuss the different Descent dive modes and how to select the right one for your dive.
Descent Dive Modes
Dive modes refer to the type of dive you are doing and/or the type of gas in your tank on a given dive. Different gases affect how long you can stay below the surface and how deep you can go. Entering this information into your dive computer ensures that you have the data you need for a successful dive. There are six different dive modes on every Descent dive computer – four dive modes and two free dive (apnea) modes. It is important to choose the correct mode and adjust the settings according to your diving situation. A Descent dive computer will remember the dive mode and settings from your last dive, so the next time you go it will automatically start with these by default.
Single gas mode: Single gas mode is the mode most commonly used by recreational divers. In this mode, you select a type of gas to use throughout the dive. Air is the gas most commonly breathed by divers, and it will be the default gas on your Descent computer. Another option – nitrox, a mixture of oxygen and nitrogen – is also gaining popularity and has several advantages, especially for a diver who wants to extend their time at a specific depth. Training before using nitrox is essential to ensure you know how to use it safely.
Multi-gas mode: In multi-gas mode, the diver can configure multiple active gases to be used during a dive. These gases can include air, nitrox, trimix and pure oxygen. This mode is primarily used by experienced and technical divers who need multiple custom gases of different types due to depth, duration and/or decompression needs.
Technical diving provides access to incredible dives not possible with standard recreational diving methods. Due to the significant increase in the complexity of technical diving equipment, procedures and planning, it is essential to obtain training from qualified instructors to perform these types of dives safely.
Gauge Mode: In gauge mode, your computer acts as a bottom timer, meaning it records the total time you’ve been submerged, from descent to ascent. You’ll also see other important information like current depth, max depth, and water temperature, and you’ll have access to important tools like a compass and stopwatch during your dive. This mode is commonly used when using your Descent as a backup on another computer.
In gauge mode, your dive computer is not able to calculate the nitrogen load during your dive. This means that it will not be able to provide a decompression limit (NDL) or a decompression instruction.
Closed circuit rebreather mode: A closed circuit rebreather (CCR) is a diving device that recycles breathing gas. In a CCR, the diver breathes in a loop, with the CCR unit removing exhaled CO2 from the diver and replacing the small amount of O2 a diver consumes with each breath. CCRs have significant advantages, especially for deep technical diving. A CCR diver will consume much less gas, breathe warm, humid air, produce very few bubbles to scare away marine life, and be able to minimize decompression time due to CCR’s ability to maintain optimal O2% in the diver’s breathing gas. However, CCRs are also much more expensive and complex than traditional “open circuit” scuba systems. Significant training is required to safely dive CCR.
Freediving mode or freediving hunting mode: Freediving simply refers to free diving or diving while holding your breath instead of breathing from a tank. When a freedive is triggered, it creates a session that can encompass many dives – common when a freediver is training, competing or heading out for a day of spearfishing. Because time is even more valuable, your computer will refresh more often and you’ll see your dive time, depth, heart rate, and descent and ascent speed. Back on the surface, you’ll get information about how long you’ve been on the surface and you can access location information.
Freediving mode disables audible alarms and simplifies the screen to provide clear information when spearfishing.
Are you looking for a dive computer?
You can find a Garmin dive computer that will help you pursue your passion for scuba diving as well as your land interests. The Descent™ G1 Series and the Descent™ Mk2 Series are watch-style computers that offer all the dive features you need plus full smartwatch functionality for every day. Garmin also offers Wireless Air integration with the addition of the Descent™ T1 Transmitter. It pairs with select Descent dive computers to monitor tank pressure, air time remaining and air consumption.