Dive gear for archaeologists part 3: computer

Dive computers all function in a similar way. They use an algorithm that, based on your depth, dive time, and gas mix, calculates your NDL. Most computers display the same metrics, and often in a similar way. They can often be set to a more conservative or more liberal mode, allowing for longer or shorter bottom times based on water conditions or exertion during a dive. Most computers can also give you a visual and audible warning should you exceed a certain depth limit, PO2 value, ascent rate, or NDL. They usually have air, nitrox, and gauge modes. Generally speaking, when it comes to basic functionalities, a $200 dive computer will serve you just as well as a $1,000 one. There are, however, numerous differences between expensive, high-end dive computers and their cheaper counterparts.

One of the main considerations when buying a dive computer is whether you want to wear it when you’re not diving as well. The cheapest computers are often big, plasticky, and heavy. While you can technically wear them throughout the day, they tend to be too big and don’t look great. Smaller computers, especially those made of metal or other premium materials, are often more expensive. They can, however, be comfortably worn all day and look more like a regular watch. You can wear them to a dinner party and not get any strange looks.

The next consideration is whether you want a computer with a user-replaceable battery or an integrated battery that can be charged. There are pros and cons to both. A user-replaceable battery usually lasts for a long time, but often dies when it’s inconvenient, at the start of a project or even as you’re about to start a dive and turn the computer on (we’ve been there many times). They can be pretty easy to replace, but there is a risk of flooding the computer if it’s not closed properly. You won’t have this problem with a computer with an integrated battery, but these usually need to be charged every few days or so.

Many dive computers these days offer an air integration option. They will connect to a transmitter that’s attached to a high pressure port on your regulator’s first stage. The transmitter relays tank pressure to your dive computer. This is very convenient and can eliminate the use of an extra hose for an SPG, making you more streamlined in the water. This way, you have all your important information on one screen. While this is a great option, it does come with a potentially serious issue. If the transmitter’s battery dies, or if the connection between the transmitter and the computer fails, there is no way to keep track of your air consumption, which means no diving. Over the years, we’ve seen different types of dive computers with connectivity issues. If you choose to use air integration on your computer, our recommendation is to always have a regular SPG connected as well. Some people choose to have their computers integrated into a console, which is a more reliable air integration setup, but does eliminate the flexibility of using your computer separately when you want to travel light and don’t want to bring too much dive gear. A fun and sometimes useful functionality about air integration is that when you download your dives to your computer, you can see how your air consumption was affected by factors such as depth or water temperature.

As mentioned above, there are now also several smart watches on the market that have dive functionality. Garmin pioneered this development with the Descent, and most recently with the Descent mk2 and GI series. A few weeks ago, Apple launched the Apple Watch Ultra, which also has built-in dive functionalities. The great thing about these watches is that they look great on your wrist and are very useful for everyday use. They are advanced smart watches and activity trackers, but also packed with dive features. The Garmin Descent mk2 is perhaps the most versatile dive computer on the market today. It can support anything from a recreational dive on a single tank to rebreather diving or a complicated technical dive using multiple gas mixtures. What’s perhaps most exciting for archaeologists is its GPS functionality. The computer records the GPS coordinates of the entry and exit points of a dive. We’ve used this functionality many times during survey dives, when it can map survey transects or sites without the need of a boat and separate GPS device. After the dive, the computer automatically syncs to an app on your phone, where the GPS coordinates are displayed on a map along with your dive profile and other information about the dive. The Descent mk2 can also connect to five transmitters at a time, allowing you to keep track of your team’s air consumption. As you can tell, we are a big fan of the Garmin computers. The Descent series comes in multiple sizes to fit anyone’s wrist. 

For basic dive functionalities, you can’t really go wrong with any computer. If you’re not planning on wearing your computer throughout the day, and only dive on a single tank within recreational limits, a Suunto Zoop, Aqualung i100, or Cressi Leonardo will serve you just fine. They are rugged computers that can take a beating during demanding projects and will last for hundreds of dives. Some of them have replaceable screen guards, so if they get scratched during work dives, you’re not going to be too worried about it. If your research will take you beyond recreational limits, we recommend Shearwater computers, which are some of the best ones available on the market today. They are rugged, have nice displays, and their smaller products can be worn all day long. If you want a computer that also doubles as a smart watch and has useful functionalities such as surface GPS, the Garmin Descent mk2 is the way to go. Whatever computer you choose will largely depend on your budget and needs. You get what you pay for though: more functionalities and smaller size usually means a higher price. Your dive computer is above all an essential piece of safety equipment that will probably outlast all your other dive gear, so it is definitely worth the investment.