Weights are an essential part of any scuba diver’s equipment. Put simply, the weights allow us to descend in a controlled manner, and more importantly, to ascend safely to avoid Decompression Sickness. However, the number of weights will be determined by several factors which you can learn more about. So why do we need weights in scuba diving and why are they so important?

Why do we need weights in SCUBA diving?

Despite many people’s fear of drowning, humans actually float quite well and are generally positively buoyant. As long as you are breathing, if you lie back and relax in the ocean you will float. This is mostly due to our body fat (fat will float more than dense muscle), and also because of our lung’s capacity for air – just imagine your lungs as big balloons that float when you inhale!

If you are wearing a wetsuit or a drysuit, then these exposure suits will also be positively buoyant in varying degrees. The thicker the wetsuit the more ‘floaty’ it is. And if you are wearing a drysuit, then you are basically a giant floating balloon!

What is a Drysuit and How does it Work?

Scuba divers, however, do not wish to float on the surface! As brave adventurers looking to explore the ocean floor, these handsome daredevils actually want to sink and find that sweet neutral buoyancy.

When you first put on a full set of scuba diving equipment on land, it will be heavy. The weight on your shoulders may give you the impression that you will sink the bottom when you hit the ocean. I mean just look at how heavy a tank cylinder is! 

However, this is where the BCD (Buoyancy Control Device) comes in. This jacket or wing style bladder can be filled with air so that all of your equipment and yourself will float on the surface of the water. This keeps you safe before you decide to descend and go for your dive.

So how do you make yourself sink to the ocean floor (or your desired depth)?

Weights of course!

why do we need weights in scuba diving?
Lead weights used in SCUBA diving

How do we use the weights to go up and down?

Weights are heavy so they will help you sink underwater. Too little weights won’t do anything, but too many weights will sink you like a stone. So determining how many weights you need is very important.

By releasing air from your BCD, the weights will pull you down. You can control this speed by releasing air slowly from your BCD or using your legs to kick and slow your descent.

Using an aluminum tank will change your buoyancy as you breathe and use your air. The tank will slowly get more buoyant, and this is when you will want to release more air from your BCD so that you do not float up too quickly. The weights will be important in controlling this.

By the end of your dive, you will need to make a 3-minute safety stop at 5 meters. Generally, your cylinder/scuba tank will be nearly empty at this point and wanting to float up. This is when those weights are very important. It allows you to stay safe and controlled at 5 meters without having to exert energy by swimming against your buoyant tank or having to exhale and empty your lungs!

Learn more about How Scuba Divers go Up and Down in the water.

The History of Weights

In the very early days of scuba diving when it first became an interest for the general public in the 1950s, equipment was limited or expensive. People made use of what they could find. The BCDs that we currently use did not exist and regulators were in their infancy. Your whole kit may have simply consisted of an oxygen tank (super dangerous!) attached to a homemade harness with a regulator, some fins and a mask. 

To get down to the desired depth, divers would find a suitably sized stone to hold on to which would drag them down to the point they wished to stop. They would then let it go and swim around for 10 or 15 minutes slowly ascending as they went.

Modern Weights

Newly created lead weights Photo: Denise McIntyre

As the sport became more popular and equipment was properly manufactured, divers required a way to remain at the desired depth. This is how the first weight belts were born. The number of weights you used would be based on experience and the depth you wanted to dive to.

Whereas before, weights were chosen to help reach the desired depth, weights were now used to make the diver neutrally buoyant at a range of depths making use of the addition and removal of air from the BCD.

Specially designed weight belts and lead weights to fit on them were created. The design has changed very little in the last 50 years.

Put simplyweights help to make a diver sink in a safe and controlled way.

What types of systems are there for carrying weights?

Weight carrying systems come in even more forms than weights themselves. The most common styles are:

Weight Belts

The most common method and taught to all beginner divers. Weights are threaded onto a simple 3-inch nylon strap with a quick-release buckle. Although a little uncomfortable for some, this is the most common and reliable method to weight yourself.

Find out How to Make a Weight Belt for Diving.

how to make a weight belt for diving
Weight belt and weights

BCD Integrated Weights

The race to make the best-integrated weight system is still ongoing. Every manufacturer tries to outdo each other with technical complexity and ease of dumping the weights for emergencies. Watch out for bright red knobs, levers, handles and pinch buckles. Pulling these will most likely result in some weight being dumped which could cause a fast ascent. Some people include some of their weights in standard zipped pockets. If you do this, remember not to carry all your weight this way as you will struggle to release weight quickly in an emergency.

Tank Weights

Some BCD manufacturers include weight pockets on the tank strap. These are particularly common on “wing” style BCD’s that have a tendency to push the wearer slightly forward on the surface. The inclusion of a couple of weights on the band strap can help counterbalance this phenomenon. And also push you into a nice horizontal trim position underwater. Usually, in the form of double-ended (top and bottom) Velcro bags, a tab can be pulled on the bottom to open the pouch and drop the weights in an emergency.

Trim Ankle Weights

Some divers are unable to position themselves level in the water. They may find their legs naturally floating up. This is very common when cold water diving with a dry-suit. One option is to use small leg-mounted lead trim weights. While these are available from some dive stores, they are not commonly used in warm water diving.

Whichever method you choose to mount your weights, always make sure you are in a position to quickly release enough weight to bring you back to the surface. Make sure your buddy knows how your weights are dumped, particularly in the case of the more sophisticated BCD integrated weight systems. Telling your dive buddies how it works may just save your life.


So, why do we need weights in SCUBA diving? The main reason is so that we can dive safely and with control. The weights, along with the Buoyancy Control Device, will allow us to go down and stay at the desired depth. The weights are also important in allowing us to go up slowly and safely which prevents a ‘runaway’ ascent, which could increase our chances of Decompression Sickness. Weights are important in scuba diving and knowing how many weights you need will make your diving much more enjoyable and relaxed!