Light is often a factor when it comes to diving, even during the day. As we descend through the water column, water filters the light and it slowly (or not so slowly) fades away. Colors are lost, as is light in general. Move into any overhead environment and light often disappears entirely.
Consequently, a good dive torch has been a staple piece of equipment pretty much since scuba’s inception. Dive torches have seen many different designs, but today’s models tend to fall into one of two categories. One looks pretty much like a standard terrestrial flashlight and the other is a canister, wherein the light-emitting part of the torch, often referred to as the head, is separate from the battery that feeds it and the two are connected with a cable.
Both designs have their proponents, and divers sometimes have very strong feelings about one over the other (so I wouldn’t be surprised if this article sparked some controversy), but I’ll attempt to explain the main differences, based on my own experience with both systems.
The standard torch
This is still the more common design; if you walk into a recreational dive shop and pick up a dive torch, this is almost certainly what you’ll come away with. Based on what type and the quality of the torch, you may find that it uses standard batteries or has an internal, rechargeable battery, which is more expensive. Materials vary from low-grade plastic for the cheapest models to highly durable metal on the pricier ones. Light output varies from something akin to a glorified candle to a beam that feels like it can melt your eyes. Prices can vary from $50 or less to literally thousands of dollars.
The canister torch
While the standard torch design covers a wide range, you’ll generally (note that I say “generally,” as there are always exceptions) find canister torches to be towards the high end of the spectrum, both in terms of build-quality, light output and price. The canister design isn’t quite as straightforward to build for manufacturers, so you’ll likely pay more for a comparable light output compared to a standard torch design. Because the battery is separate, it is possible in many cases to put a larger battery, with higher capacity, on a canister torch. This means you’re likely (though not necessarily guaranteed) to get more battery life from a canister. It’s carried, during a dive, with the battery pack attached to your dive-rig belt if you’re using a tech setup, or on the dive-tank strap if you’re using a jacket BCD. You’ll hold the torch head in your hand, often using something called a Goodman handle, which allows you to open or use your hand without dropping the torch head.
One of the main advantages of the canister light, as explained by its proponents, is that instead of carrying your entire torch in your hand, you simply have the torch head attached to the back of your hand using a Goodman handle. This allows you to use your hand to operate gear, hold onto a line reel or an underwater scooter, or to do a pull-and-glide while cave or wreck diving. Also, if you need a lot of light and a lot of battery power, you’ll most likely need a large, heavy battery, and this is carried more easily when attached to your BCD rather than in your hand. So for wreck and cave divers, as well as for advanced technical divers (who undertake very long decompression dives), the canister torch has a lot of merit.
Apart from that, whether you prefer one or the other is largely a matter of personal taste. Some find the cable that unites the torch head and battery pack on the canister light to be cumbersome and prefer the easier approach of a simple flashlight design. A few organizations, typically those that focus on more advanced technical diving, such as wreck and cave diving, require you to use a canister. Most organizations are indifferent, though, as long as the light works.
Some claim that a canister torch always has superior light output compared with the flashlight types. This not entirely correct. As mentioned before, most cheaper dive torches are of the flashlight design, and these will often have quite low output. But a high-end flashlight-style dive torch can in many cases put out 3,000 lumens or more, which rivals most and exceeds a lot of canister dive torches.
The main drawback of the canister design is the price. While there are a few “recreational” canister torches out there, the best ones are quite expensive, and it’s often possible to find a flashlight type with the same light output at a much lower cost than a canister torch.
Ultimately, though, unless you regularly participate in advanced cave diving, or deep-penetration wreck diving, the advantages (and disadvantages) of the two designs come down personal taste, as mentioned before. If most of your diving is done in open water or on shallow reefs, and you feel the canister torches are a bit pricy for you, a good quality flashlight design will serve you just fine. But if you are looking for that extra battery life, and like the idea of the smaller torch head leaving you free to use your torch-carrying hand, then investing in a canister light might be worthwhile after all.