Using a snorkeling dive flag is a really good idea if there are boats around, to make yourself more visible, so you don't get run over. It could truly be a life or limb situation, and using one is sometimes required by law.
But we have to admit that in the past we hated using a dive flag, because most of them are just not well designed for snorkelers. Most are too big, and are designed to be used with long lines that get caught up in your fins. More about those products later.
What we now use and love is a product (review below), that while
technically not a dive flag, does work great as a highly visible marker
buoy, making it far less likely that a boat will miss
seeing us on the water. You can see that Galen in the picture below would not be easy to see without the bright floating surface marker.
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Technically, a dive flag is supposed to be a recognized navigation aid with a red background and a white line across it. Boaters are supposed to know what it means, and are not supposed to come within 50 to 100 feet of one. Divers sometimes anchor their flags in one spot to the bottom with a long line, and then return to that area when resurfacing. Sometimes they drag the flag around.
What we use as a snorkeling dive flag is a Swim Bubble by New Wave. We love it, which is saying something, given how we normally feel about dragging these things around. Yes, it is not technically a dive flag. But honestly, most boaters don't even know the laws around dive flags. And lots of dive flag products use different colors. We just call it a snorkeling marker buoy, or surface marker.
You can see in the picture below that the cruise ship in the background is keeping its distance. Seriously though, even though Nicole is already more visible with her bright colors than Galen above, the Swim Bubble really helps her be seen.
New Wave designed the Swim Bubble for open water competitive swimmers, to make them visible by boaters on the water. They have it really figured out for the right size, and belt and strap lengths, that really works while swimming. And it works great as a snorkeling dive flag. It is very compact when not in use. In fact it will fit in a pocket. It is easy to blow up and does not leak. It comes with a good belt, and a tether that attaches the bubble at just the right distance from your waist so that it does not interfere with your fins while you are kicking. In addition to being a good surface marker, it can also be used as a buoyancy aid if you are getting tired. It has a handle on it which makes holding on to it easy. Although we did not find we needed the handle, so we cut it off so it would fold down smaller when put away.
New Wave also makes a similar but different product called a Swim
Buoy, made of the same PVC material. The Swim Buoy has a separate dry bag chamber for taking a few valuables or snacks with you. You put your stuff in it, seal up the roll down
top, and then inflate the other chamber. They make the Swim Buoy in two
different sizes, and in two different materials. We have one of the
smaller 15L versions in the more durable TPU material. You can see it below on the left next to our Swim Bubble. They are about the same size. The also make the Swim Buoy in a
larger 20L version. Since we use a waterproof box for our valuables we prefer the Swim Bubble as a snorkeling dive flag.
If you do use a Swim Buoy, we highly recommend you first put your valuables in either a ziplock bag, or another dry bag before putting it into the Buoy, because these roll top dry bags are rarely 100% waterproof.
Many tropical destinations actually have laws that a dive flag is required for both divers and snorkelers, at all times. For example Hawaii requires it of all snorkelers, although it is almost never obeyed.
We personally only use a snorkeling dive flag when we are in open water that is frequented by boaters. We don't bother taking one on these wonderful guided snorkeling trips, where we are with a group of snorkelers, and guides are watching out for boats. But, when we are out exploring destinations for our eBook snorkeling guides, we evaluate the risk of encountering boats at each location. If the snorkeling spot is near a marina, or boat launch, and we are out in exposed waters, we use one. If jet skis are rented or in use in the area we definitely use one. For example, in Curacao recently, we only used it at four of the 25 spots we snorkeled.
Based on studies from Mustang Survival (they make ocean survival suits), we selected florescent green as the most visible by boaters. You can read more about that study here. But any of the bright colors available from New Wave will be very visible.
Even if you have a snorkeling dive flag, do not assume boaters are paying attention to where they are going. If you hear a boat pop your head up right away and watch them. You may have to scream bloody murder and swim quickly out of their way if they are not paying attention and you want to keep your limbs. A loud waterproof whistle might also be a good idea to have on hand in boating areas as well.
Note that you are not going to be able to freedive down with this attached to you. In our case Nicole has it attached to her belt since she does not dive. In those situations Galen sticks close to her and is then free to dive down. You could also pass one back and forth as needed. It's possible you could trail the bubble or buoy behind you on a longer line, so that you can free dive down, but that is problematic and potentially dangerous. The long line tends to get caught up in your fins when you kick. And if the line gets caught around something underwater, and it prevents you from surfacing, you could die. Not to mention the possibility of the line getting caught in a boat motor. At the very least, if you use this long line method, your belt should have a quick release system like a diver's weight belt, and at the first sign of a problem you should release the belt.
Another option is to attach a small weight to the bubble, and just leave it on the surface as you dive down. Without the weight the bubble would very quickly blow away on the surface. But the weight will slow it down, so that you can recover it when you return to the surface.
Dive Flag Float for Snorkelers?
A Dive Flag Float is one of the most common products available, and affordable. You blow it up after putting some water inside first so that it stands up correctly. There is an attachment point on the bottom for a line. We don't like them for snorkeling. They are a bit unwieldy, and if used as designed, with a long line, it gets caught up in your fins while kicking. And it does not pack down as small.
Typically this product and the ones below are used with a spool of line called a finger spool. The problem we find with the spool method is that you have to keep it in your hands the whole snorkel, managing the length of the line, etc. We don't have free hands for doing this as we have cameras and are taking pictures.
Dive Sausage for Snorkelers?
We have tried one of these Dive Sausages. They can be anywhere from four to seven feet long. They seem like a good idea as a snorkeling dive flag, because deflated they are fairly small, and it would seem they would stick way up in the air, greatly increasing your visibility. The problem with them is that unless you constantly hold them upright with your hands while snorkeling, they lay flat on the surface, making them less visible than our Swim Bubble. We tried attaching a dive weight to the bottom of one to help keep it in the air, but it was not very effective. If there is even the slightest bit of wind it gets blown over with ease, even with the weight.
Dive Torpedo for Snorkelers?
Dive Torpedos are more like the shape of the Swim Bubble we use, but are much larger, and have a dive flag on top. They tend to have a lot of attachment points and hand holds, and can make for a good place to relax if you are tired. They are generally too long to attach at your waist, without kicking it, so you need to trail it by a line, which also gets caught in your fins. They also get dragged around more by wind and waves, making towing them through the water more difficult. They are also much larger when deflated.
On our Snorkeling Equipment page, you can find a lot more first hand tips on snorkeling gear we use, have tested, and love.