You can encounter a few different water visibility problems when snorkeling. They can be dangerous at times, just annoying, or even downright weird, depending on what conditions you are experiencing. Good clear underwater visibility, where you can see a long ways, is what you want when snorkeling. And it is a good idea to avoid low visibility situations. Let’s take a look at four different types of water visibility problems that a snorkeler can experience, and a few related safety tips.
Suspended Particle Sediment
This is the most common water visibility problem when snorkeling. Basically, a bunch of sand, dirt or other sediment is all churned up and hanging in the water, making it difficult to see, like in the picture below.
Most snorkelers have experienced cloudy water like this. Typically this happens when the waves and wind are up, and you are snorkeling from a sandy beach. As you enter the water, particularly close to shore, you may not be able to see more than a foot in front of you. Clearly this is dangerous because you could run into something. In the case of a sandy beach, getting churned up by waves, the water clarity will often get better the farther you swim out into deeper water. So sometimes it is worth pressing through. But don’t stay in an area of very low visibility and try to snorkel.
Often, if a river or stream flows out into the bay or area you are snorkeling in, there is a lot of sediment in the water. If it has been raining recently and there is a stream or river emptying into your snorkel spot, avoid it for a while so the sediment can settle out.
Suspended sediment lowering visibility is one reason why you want to avoid kicking the ground or sand in the area where you are snorkeling, because you can churn up a lot of it that may take awhile to settle back down. This is particularly important when snorkeling in mangrove areas.
Halocline
Have you ever been snorkeling and it seemed like you could not focus on anything, almost like your vision was blurry? It may get better for a while, and then much worse? Or if you dive down it will suddenly get clear? If so, you likely experienced a halocline, and it can be a very weird experience. In our experience, this is also one of the most common water visibility problems when snorkeling.
What is happening is that two different layers of water have different salinity levels. This happens most often when there is a source of fresh water entering the sea. It can be from a river or stream, a freshwater spring that emerges in the ocean floor, or even from rain.
One time, snorkeling in Curacao, it rained so hard on us that a very thick halocline layer formed of fresh water on top of the sea water, which you can actually see in the picture of Nicole. Notice how her face and mask are extremely blurry, and just below the fresh water line her camera is not so blurry. We shared this story in our newsletter and heard from lots of people who have experienced haloclines.
Snorkeling in a halocline can actually ruin your experience, because it prevents you from seeing anything clearly below. If you dive below the fresh water layer, you can normally see better.
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Thermocline
A thermocline is also a situation where there are different layers of water, but these are formed because of differences in temperature, instead of salinity. Particularly if you freedive you may feel a sudden change in temperature, and sometimes there is a visible border between the layers that may look like an oil slick, although thermoclines don’t tend to disrupt your vision as much. This is not one of the more common water visibility problems when snorkeling. We just don’t see them as much as we do haloclines. It is more common in areas of stronger currents, where different flows of water encounter each other.
Algae and Bacteria Blooms
Sometimes water conditions become ideal for algae or bacteria to start growing rapidly, and it can fill the water to a noticeable amount, creating lower visibility. Sometimes there is a color associated with the bloom. That is one reason why we recommend visiting Bermuda early in the summer, because as the water warms up later in the summer they often have a big bloom, which really lowers the visibility. In the picture below the cloudy water is from an algae bloom in Bermuda.
And in Indonesia, there are places where there is so much algae and bacterial life in the water that having a little less visibility is to be expected. This is one of the more serious water visibility problems when snorkeling, because if you have an open wound, or if you ingest the water, infections can occur. So be very cautious about any open wounds in waters experiencing a bloom.
Sharks Are More Dangerous in Murky Water
Murky water might be one of the more dangerous water visibility problems when snorkeling. We are not generally afraid of sharks. We are not their food. But if you are snorkeling in really murky water, it is much easier for a shark to become confused about what you are, and this is thought to contribute to shark attacks. In places where we know shark attacks are more common we stay out of murky water. Hawaii includes that in their list of shark safety tips.
How to Avoid Water Visibility Problems When Snorkeling
Avoid Snorkeling in Windy and Wavy Conditions for Better Visibility
There is nothing like snorkeling in crystal clear water where you can see for hundreds of feet. But your chances of experiencing good underwater visibility on a really windy and wavy day, particularly close to any shorelines, is low. This is one of the big reasons why we look at wind speed and wind direction forecasts before we go out snorkeling. We use that information to pick a location that is protected from the wind. And many tropical locations have wind cycles, where it is calm in the morning, and it gets windier in the afternoon. So we go early to avoid wind related water visibility problems when snorkeling.
Pick Less Rainy Seasons to Visit
Rain causes water visibility problems when snorkeling. Whenever we can, we visit snorkeling destinations during seasons of less rain. Because when there is lots of rainfall, not only can you experience more haloclines, but also you get a lot more runoff from the shoreline, which brings with it suspended sediment. Rain can also contribute to algae blooms because of the rich nutrients that get washed into the ocean, promoting growth. Learn more about using weather websites to plan snorkel trips.