Is Scuba Diving in Freshwater Different from Saltwater

Scuba diver - Is Scuba Diving in Freshwater Different from Saltwater

Having dived in freshwater and saltwater (seawater), and knowing that people ask about the difference between these two types of diving, I thought I’d answer the question about is scuba diving in freshwater different from saltwater diving.

Freshwater diving vs saltwater diving are different by increased buoyancy in saltwater, colder temperatures in freshwater, tides and currents in seas vs little to none in lakes, and generally better visibility in saltwater. Aquatic life and wreck diving are also more exciting in the sea vs lakes.

All of my freshwater dives were either when I was being trained when I first started diving, or later in my diving experience when I was teaching divers in a lake on their first dives. Whereas most of my diving in saltwater in a marine environment have been for recreational reasons since getting certified to dive over 30 years ago.

As an aside, in this article about where to find great white sharks, you may be as surprised as I was to discover some of the places where you find great white sharks! Place number 6 is the one that surprised me the most, but if you live in the States, you may be more surprised at places two, three and four.

Differences between freshwater diving vs saltwater diving

Buoyant diver - Buoyancy difference between freshwater diving and saltwater diving

1. Buoyancy

The first difference between freshwater diving and saltwater diving is how they affect your buoyancy. Buoyancy control is one of the most important techniques to master when scuba diving, and one that many novices struggle to master in the beginning.

This is a good reason why it’s important to know how buoyancy is affected when diving in different environments, which in this case is freshwater vs saltwater.

Saltwater is more dense than freshwater, which means you’ll be more buoyant when you dive in the sea. If you’re more buoyant, and with everything else being equal, you’ll need more weight to be neutrally buoyant in saltwater.

That being said, most big lakes are very cold (see next point), which means you’ll need a thicker wetsuit or better still a drysuit to dive in a freshwater lake. The thicker the wetsuit, the more weight you’ll need to achieve neutral buoyancy, and drysuit diving means you’ll need more weight too.

You will need to do a weight check before you dive in freshwater if you’ve only ever dived in saltwater before, and visa versa. For example, I dived in a freshwater lake in June 2021 with pretty much the same dive kit as I used for a dive in saltwater in September in the same year, which in both cases was diving in a drysuit, with the only exception of what kit I used is how much weight I needed.

The weight I used on the freshwater lake dive in June was not enough for me to even get below the surface when I dived in the sea in Cornwall in September.

But then fast-forward to December of the same year, when I dived in Barbados in saltwater, the weight I used for these dives was less than both dives in the UK in freshwater and saltwater. This is because I was diving in a thin wetsuit in Barbados, which is less buoyant than my drysuit.

So whilst saltwater diving offers more buoyancy than freshwater diving, at the end of the day for you to achieve neutral buoyancy is not only about whether the water is fresh or salty, it is also about your dive kit too.

Divers in icy freshwater - Water temperature difference

2. Water temperature

Freshwater lakes tend to be colder than the sea, as lakes don’t have currents to move the warmer water around (see next point). For example, in the UK we have the Gulf Stream, which is a current of warm water from the Gulf of Mexico that keeps our seawaters relatively warm when compared to the freshwater lakes that are much colder.

The same Gulf Stream current also affect the east coast of America too, without which the temperature of the seawater off places like Charleston and Myrtle Beach in South Carolina and Virginian Beach in Virginia would be much colder.

Large bodies of freshwater don’t benefit from these warm water currents, and in the case of the deeper lakes the deep water stays cold. Cold water is more dense than warm water, which means that as the surface of a lake warms in the summer, it’s more likely to remain on the surface. This is why you often get thermoclines in lakes, which can be very noticeable as you descend on a dive in freshwater.

Shallower lakes will get warmer in the summer months, especially in the shallows along the shoreline, which means you may be able to dive in a thinner wetsuit, or even in a shorty.

Water temperature affects your air consumption when diving, as it affects your calorie burn too, which means you’ll likely consume more air and burn more calories on freshwater dives.

When I dive in lakes and quarries in the UK I tend to use my drysuit, as I do when diving in the sea, even in the summer months. But if I dive in the tropics I use a wetsuit instead, and many divers use a shorty or even just a Lycra body glove.

This means that your exposure suit is not necessarily governed by whether you’re diving in freshwater or saltwater, but it is affected by whereabouts the water is, the time of year and how deep the body of water is.

3. Currents

One important distinction between freshwater vs saltwater diving is that most freshwater dive sites have little to no currents, whereas the sea has many currents. The currents in saltwater seas and oceans are created by tidal movements caused by the moon, and currents like the Gulf Stream in the Atlantic Ocean.

Currents can be dangerous (please read this article – How To Deal With A Down Current And Not Panic – escape The Abyss), but can also be great fun, which is called drift diving.

If you want to find out more about drift diving, this article “what is drift diving” explains all you need to know. The article includes 20 pro tips for drift diver beginners.

The exception to this rule is freshwater rivers, which obviously have currents. But it’s not common to dive in rivers, except that some estuaries are dived, assuming the visibility is good enough and the currents aren’t too strong to make it dangerous to dive. But estuary dive sites tend to only be dived safely on a slack tide.

As already explained, this difference between freshwater diving vs saltwater diving is exploited by dive schools, as freshwater lakes tend to be safer for beginner divers because they don’t have currents. But never under estimate diving in a lake, as the same rules of diving safety apply in a lake as they do in the sea. Many divers have lost their lives diving in lakes by running out of air and such like.

4. Tidal difference

An important difference between freshwater and saltwater is that freshwater lakes are not affect by tides, whereas the seas and oceans are.

Tides affect when you can dive in certain places, for example you may only be able to dive on certain wrecks on a slack tide, otherwise you’ll be swept off the wreck. Also, as already explained above, it may only be safe to dive in an estuary on a slack tide.

Your entry and exit points for shore dives can alter depending on the state of the tide, which is an important diver planning point before you enter the water, as you need to know before you enter the water that you’ll be able to exit safely.

Cenote diving - Visibility difference

5. Visibility

Water visibility is affected by many things, which include the temperature of the water, currents, tidal movement, the type of bottom material like sand or sediment, plankton blooms and algae, which will be different for freshwater vs saltwater.

I have dived in poor visibility and good visibility in both freshwater and saltwater, so it’s not necessarily correct to say that one is worse than the other. But it does depend on where you dive.

For example, the visibility in the sea in the UK is mostly less than a few metres or feet, but I have dived when there’s been 20+ metres (66 feet+) of vis, which was a deep wreck dive off Littlehampton (47 metres deep to be precise).

But I mostly blue-water dive now in places like the Caribbean where the visibility is mostly 20+ metres, and if it’s less than this in the Caribbean, most would describe this as poor visibility.

When it comes to freshwater diving, one of the problems with many lakes is the sediment on the bottom. The sediment in lakes tends to sit on the bottom, and because it’s so fine it doesn’t take much to be disturbed by diver’s fins.

The second problem is the sediment stays in one place for a long time, as there are no currents to carry it away. Not a problem if you swim away from the disturbed area, but a big problem if you’re trying to teach newbie divers a skill, a good reason why they have training platforms at Gildenburgh Water (freshwater lake in the UK).

Also, if you are unfortunate enough to dive in freshwater after a group of divers have just dived, your visibility on the same dive may be compromised, especially if the group of divers before you included novices.

I’ve dived in Gildenburgh Water when someone has disturbed the sediment and you cannot see anything.

I also recently helped someone fix a fountain in a large lake, which meant I had to kneel on the bottom to do so. The problem was that I stirred up the sediment which was difficult to prevent, which meant I could hardly see what I was doing unless my mask was almost touching the pipes I was fixing.

There are exceptions to most rules, and in the case of freshwater the cenotes in Mexico are the exception as far as visibility goes. Cenotes are gin-clear and in most cases offer better visibility than almost any dive in saltwater.

Sea turtle - Aquatic life difference

6. Aquatic life

One other important difference between freshwater diving vs saltwater diving is the aquatic life you see.

The aquatic life (marine creatures) in the sea are far more exciting than the creatures you see in freshwater lakes. In saltwater you get to dive with sharks, turtles and dolphins, not to mention the seals in places like the Farne Islands.

Whereas in a lake you’ll be lucky if you see a perch or perhaps some roach or rudd. But then if you’re really in luck you may see pike, which I compare to barracuda. Both are predatory fish and both tend to similarly ‘lurk’ in the water.

If you want to dive for marine life, you are far better to dive in saltwater. But having said that, you need to dive in the right location to see good marine life. For example, if you want to dive or snorkel with whale sharks (<— click this link to find out more, as this is an awesome experience by the way), you need to choose your location carefully.

7. Wreck diving

If you’re into wreck diving, you are far better diving in the sea because this is where ships sink. The only wrecks you’ll find in freshwater lakes are what has been deliberately sunk for the purposes of diving. For example, in Gildenburgh Lake there is a double-decker bus you can swim through, and in Stoney Cove (another freshwater lake in the UK) there’s a sunken plane and other artefacts of interest.

But if you want to dive on ship wrecks, you need to be diving in the sea, and if you become a real wreck diving enthusiast, you may even get the chance to scuba dive the wrecks of Truk Lagoon too.

8. Diver training

Freshwater lakes are good for diver training because the body of water is enclosed and lakes don’t suffer from the same currents and tides experienced in the sea or saltwater.

For most inland diving schools, lakes are one of the best places to complete first dives after pool training for newbies, as they offer a safe environment for beginner divers to practice and perfect their mask clearing and buoyancy control for the first time.

Having said that, many of the diving schools in places like the Caribbean, Australia and Florida will use a shallow saltwater reef for their beginner’s first open water dives where there are no currents.

Mountain lake - Altitude difference

9. Altitude

When you’re diving in the sea, you are diving at sea level. Whereas when you’re diving in a lake you may be diving at higher altitudes. The altitude of your dive will affect your decompression status from one dive to the next.

The standard dive tables and dive computers are set for diving a sea level, which means that if you dive above sea level in a lake you need to take this into consideration when planning your dives, decompression times and dive intervals.

10. Saltwater affects on dive gear

The salt in saltwater is highly corrosive, which is why all metal parts on your equipment should be made using marine quality stainless steel. But it’s not just the metal parts of your diving equipment that are affected by the salt, it is everything else as well.

This is why it is important to rinse off your dive kit properly after every dive in saltwater. If you don’t, your dive kit will not last as long and the salt residue will eat away at your kit.

Whilst freshwater doesn’t have the same levels of salt in the water as seawater does, it is still good practice to rinse off your dive kit after every dive. Freshwater can leave your dive kit smelling, and if you don’t rinse off the residue from a lake, your dive kit can become very smelly and begin to rot.

But you also need to take care to not cross-contaminate from one body of freshwater to another, which is another good reason to rinse off your dive gear after a freshwater dive too.

Shark - Aquatic life difference

Final thoughts on scuba diving in freshwater vs saltwater

If you live in a “land-locked” country and want to dive, you may have no choice but to dive in freshwater if you don’t want to travel all the time.

On the whole, it’s true to say that most divers dive in a marine environment only, that is saltwater. Marine diving (saltwater diving) is seen as more exciting, often with far better visibility and mostly the water is warmer, with a much bigger variety of aquatic life and ship wrecks to enjoy too.

Also, please don’t leave before you watch the video in this articleI almost don’t want to spoil the end of the video, so all I will say is it involves a carcass, many sharks and a single grouper…you may be surprised at what happens, I certainly was!

I hope you enjoyed this article about is scuba diving in freshwater different from saltwater

I’d love to hear from you. Tell us about your adventures of diving and snorkelling. Please use the comments section below. Please also share your photos. Either from your underwater cameras or videos from your waterproof go-pro’s!

If this article hasn’t answered all of your questions. If you have more questions either about snorkelling or scuba diving (or specifically about is scuba diving in freshwater different from saltwater), please comment below with your questions.

There will also be many more articles about scuba and scuba diving safety tips (and on snorkelling too) for you to read and learn about this fabulous sport.

Have fun and be safe!

Is Scuba Diving in Freshwater Different from Saltwater

Article written by Russell Bowyer who has been a scuba diver since diving on the Great Barrier Reef in Australia in 1989. After his first dive he trained as a BSAC diver in the UK. He attained his Diver Leader certification with BSAC. He then went on to become a scuba diving instructor, teaching others how to dive and was voted as Diving Officer and Treasurer for the Saffron Walden BSAC club too. Russell has dived all over the world, including the UK, on liveaboards in the Red Sea, the Caribbean, South Africa and the USA. Russell is experienced in all dive types, including drift diving, deep dives that involved decompression stops and recreational dives too.

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