The entirety of the ocean makes up for just over 70% of the planet’s surface. It’s been that way for as long as humans have been on the Earth.  And despite all the time we’ve had to explore and gather data on it, we still know very little about the ocean.

Specifically, we don’t know much at all about what’s going on in the depths. In what is an even more shocking statistic than the one above, 80% of the ocean remains unexplored as of 2021. And that’s not a typo.

80%?! Really?! Yep. As crazy as it sounds, this species of ours has sent people to walk on the surface of the moon, and robots to roll around and explore on another planet, and yet we’ve only discovered about 20% of something which a lot of us can see from our bedroom window?

It does seem a little strange, but it’s not without reason. There is just way too much pressure in most of the ocean’s depths for us to be able to do any kind of worthwhile investigation. We have yet to figure out how to ensure that both the divers and their equipment can survive down there.

This doesn’t mean that we won’t get a handle on that someday, but it’s a process that is probably too dangerous for us to rush. In a way, it’s kind of exciting that there is so much mystery still left in a world where information is so readily available.

And even though there’s still a lot we don’t know, we are discovering more and more about the ocean every single day, and it’s something that fascinates an awful lot of people. People sail, surf and scuba dive as hobbies, just to experience the ocean up close.

It’s also something that has long been the subject of art and inspiration for creative types, and images of ocean waves are a popular choice for tattoos.

It’s fun to think about how different everything is just below the surface. One such difference is how sound works. Many people understandably believe that the ocean is silent, but that’s not the case. 

There are actually a ton of different ocean sounds down there from a huge variety of sources. Let’s take a look at what kind of sound is down there:

Human-Generated Ocean Sounds

Sound that comes from human activity, also known as anthropogenic sound, makes up a huge part of the ambience present beneath the waves. As our technology advances, our ability to utilize the ocean for our own advantage increases with it. 

We use the ocean for large-scale transportation, and this means that there is a constant stream of freighters and supply ships crossing back and forth all over the ocean. There’s also oil to think about. 

Most of the world still relies a lot on oil, and there are only a few places where it can be acquired. This means that large tankers are needed for transportation, and these are even louder than the big supply ships.

But as far as the ships are concerned, the loudest are unquestionably the icebreakers. Huge, special-purpose ships which do exactly what you would expect them to do, and that’s break through ice so that other ships won’t be inhibited on their passage.

It’s not just ships that make up the anthropogenic noise underwater, but also our military presence. Active sonar is used by military vessels both during training exercises and to search for enemy ships and submarines.

Most large militaries mainly use mid-frequency sonar, and even that creates about 235 decibels (dB) underwater. We think of these things as being quite practical and beneficial for us, but in truth, the amount of noises humans are generating is causing problems for marine life.

When we swim in the ocean, we can’t hear all of this stuff very well, despite the fact that sound travels faster underwater. This is because our evolution has resulted in ears that are designed to pick up noise through the air.

Creatures that evolved underwater have a different auditory capacity, and one which is not used to anthropogenic noise. There are a whole host of consequences from this. Some creatures are being driven from their natural habitat due to what they perceive as the sound of threatening creatures.

Fish also utilize sound for their mating calls, and this is more difficult for them when there is all of this other noise getting in the way. It has resulted in certain species facing extinction due to their survival and reproductive habits being infringed upon.

Marine life is important and so this is definitely something that we should try to take steps to reduce. Speaking of marine life:

Marine-Life Generated Ocean Sounds

Though marine animals are much more present in the ocean than our ships and military vessels, they actually make a bit less noise. Even the biggest and most powerful marine mammals that we are aware of only generate about 220 underwater dB.

This is a bit less than what the military’s active sonar is capable of. Regardless of how much they produce, underwater sound is far more important to these marine creatures than our sound is to us. 

As we mentioned above, sound is how these creatures are capable of finding each other in the vast, open water and it’s also how they attract their mates. Which is, of course, essential for the survival of their species. 

There is a huge variety of different kinds of creatures down there and so as you would expect, there is also a huge variety of different kinds of sounds. From blue whales, humpback whales and bowhead whales, the sound is almost like a moan.

It’s deep and tonal and is commonly referred to as ‘singing’ by marine biologists. But even within this category, these whales are capable of many different kinds of moans, and can actually produce even more individual sounds than humans can.

And then you have sperm whales who communicate through a clicking noise, and at their most powerful, these clicks are actually the loudest ocean sounds that any marine mammal is capable of producing.

There are also other kinds of whales which use more a pulsing call and then there are dolphins which use whistling sounds, and there are no doubt numerous other undiscovered animals found even deeper which have entirely unique sounds of their own. 

So no matter how we perceive it when we go swimming or diving, the ocean is most definitely not a silent place. It’s full of sounds from both humans and animals, the latter of which is far more important than we realize. 

For the benefit of these amazing and beautiful creatures that we share the earth with, we should take their reliance on sound more seriously and do what we can to stop infringing upon it.