What thickness of wetsuit do I need?

Types of wetsuits

Whether you’re an avid surfer or love going on an extended underwater dive, one of the most important investments you’ll make is choosing a high-quality wetsuit designed to handle your activities.

Having a properly fitted wetsuit can often be the difference between enjoying the waves and water for hours on end or calling it a day early as you shiver and try to stay warm.

When looking to invest in a wetsuit, it’s essential to know that not all wetsuits are created equal. Some are explicitly built for diving, while others help you catch that big wave. The key factor in determining the type of wetsuit you should buy ultimately depends on the temperature of water in your activity area.

A 6/5mm wetsuit, for example, will work to keep you warm in frigid waters while a 2mm or 1mm wetsuit is best suited for warmer water beaches or other tropical climates.

The thickness of the neoprene on the wetsuit is only part of what makes a wetsuit unique. The style of the design also plays a significant factor in choosing the best wetsuits for you.

Here are a few common types of wetsuit styles as well as their strengths and weaknesses.

Wetsuit Jackets 

Wetsuit jackets are wetsuits designed to look and feel like a jacket. They cover your entire upper torso and are generally used when waters are likely to be on the colder side.

Wetsuit Vest

A wetsuit vest is considered to be one of the more minimally designed wetsuit options and leaves your arms and shoulders exposed to the warm sun. Perfect for surfing in warmer weather, the wetsuit vest offers protection from the water while giving you the flexibility needed to paddle out on your board and chase that monster wave.

wetsuit vest

wetsuit vest

Short John Wetsuit 

This type of wetsuit leaves your arms and shoulders exposed while covering your torso and thighs. Offering more protection than a wetsuit vest, this is an excellent option if you want a little more coverage but not at the expense of flexibility and comfort.

Short John Wetsuit

Short John Wetsuit

The Long John Wetsuit

Imagine putting on your Long John pajamas and going for a swim — that’s exactly what you get with the Long John Wetsuit. While not quite a full-fledged wetsuit, the Long John wetsuit covers your torso to your feet leaving your arms and shoulders uncovered.

Long John Wetsuit

Long John Wetsuit

The Spring Wetsuit 

Designed for plenty of coverage, the spring suit covers torso but leaves your arms uncovered as if you were wearing a short sleeve shirt. A popular choice for surfing or diving in warm waters, it offers the perfect mix of coverage and flexibility.

The Full Wetsuit 

Covering you from head to toe, the full wetsuit offers maximum protection and is perfect for going for a deep dive in chilly water. A little less flexible than other wetsuit options, it is built with the purpose of keeping you warm under harsh conditions.

Full Wetsuit

Full Wetsuit

How A Wetsuit Works

If you’ve never experienced the magic of a wearing a wetsuit before, it’s truly a one of a kind feeling. Contrary to popular belief, wetsuits do not keep you completely dry! You will, in fact, come in contact with the water when wearing a wetsuit.

That said, the suit is designed to help you retain heat even with exposure to cold water. The wetsuit works by holding in the first layer of water that you encounter, keeping additional cold water from coming in.

Think of a wetsuit as a coat that you wear in the water! You’ll still feel the cold, but it will do its best to keep you warm.

While the main layer of a wetsuit consists of the synthetic rubber neoprene, most wetsuits are built with multiple layers, offering additional protection from the water. Depending on the type of wetsuit you choose, each layer will consist of different materials that work to keep you warm.

For a wetsuit to be effective, it’s imperative that you have a proper fit. A wetsuit that is too big will be unable to contain the initial water you encounter. That means you’ll be continuously exposed to cold water.

You want a tight fit to ensure proper insulation. It should not be uncomfortable, but the wetsuit should be quite snug.

Water Temperature

When looking to purchase a wetsuit, the number one factor you should consider is the type of water you’ll be surfing or diving in.

If you plan on doing deep dives in extremely cold water, you wouldn’t want to choose a thin wetsuit vest.

Choosing a wetsuit that is designed for extremely cold temperatures is also not the best choice if you’re planning to surf in the warmer tropical waters. These are bulky and will not perform well, hindering you surfing abilities as well as your enjoyment.

Wetsuit flexibility an important part of choosing the right suit for you!

Wetsuit Thickness 

O’Neill, one of world’s most popular action sports brands, carries seven distinct types of wetsuits based on neoprene thickness. Each is designed based on the temperature of the water and activities you’ll be enjoying while wearing your wetsuit. 

Here’s a brief overview of the types of wetsuits that are available in order of neoprene thickness.

Note — “mm” refers to the millimeter thickness of the neoprene material found around the core and torso of the suit. The higher amount of mm, the warmer you’ll be! You can see the wetsuit thickness chart below!

Wetsuit Temperature Chart

Wetsuit Temperature Chart

UV Lycra

 Suitable for the warmest water temperature, this style of wetsuit offers protection from the water as well as the sun. You will likely wear this choice in a hot, sunny climate, so you will need to guard your skin against harsh UV rays. A UV lycra wetsuit is very light and offers the most flexibility.


For slightly colder climates than the UV Lycra, the 1mm again is a fantastic wetsuit for waters that are on the warmer side — think 70 - 80 degrees F. That temperature might sound nice,  but you will get cold after a day in the water. Although the climate may be cooler, you’ll still be at risk of damaging your skin in these environments. 


A middle tier wetsuit option, the 2mm is suitable for both warmer waters as well waters that might become a little too cold to swim in after a few hours of fun. The 2mm is recommended for waters in the 55 - 65 degree F range.

3/2 mm and 4/3mm

A true full body wetsuit, this amount of neoprene thickness works to keep your body warm in waters that are getting seriously cold. While it won’t block out all of the cold, it offers plenty of protection!

4/3 mm and 5/4mm

As the thickness of the neoprene material continues to increase, picking up this wetsuit means you’ll be exploring some incredibly frigid waters. While not the warmest option, you’ll be comfortable diving or surfing in waters in the 48 - 54 degree F range.

5/ 4mm & 6/ 5mm

Is water even a liquid at these temps? The second warmest wetsuit option available, this will keep you going in waters ranging from 40-47 degrees F. 

6/5 mm & 7mm

Last but not least is the wetsuit specifically designed for you to explore some of the coldest temperatures that aren’t quite frozen. If your destination involves wearing a few layers of socks and three pairs of gloves, this wetsuit is calling your name.

Again, not only should you choose a wetsuit based on the specific suit style that you’re most comfortable with, you want to ensure that you’re selecting the right wetsuit thickness based on the expected temperatures of the water you’ll be in.

Other Considerations

While we have covered the importance of the style and thickness of the wetsuit when choosing the one right for you, there are a few other factors to take into consideration.

Your activity

Depending on whether you’ll be primarily surfing or diving with your wetsuit, you might want to choose a suit that has a little more flexibility or padding. When surfing, you’ll undoubtedly suffer a few bumps and bruises from some nasty waves. Having a thicker wetsuit can often help reduce the impact from a hard fall. Additionally, every wetsuit stretches a little differently, which can have a large effect on overall comfort.

Your personal taste

You may like a suit with a little more flexibility, while others might prefer a tighter fit. Ultimately, as you get more and more comfortable with wearing a wetsuit, you’ll be able to discover your personal preferences on what suit works best for you. When deciding which to choose, make sure you get the right size as well as invest in the style that will work for you. We hope this guide has given you an idea of the range of options available. Now, once you've decided what you're going to need for the type of water you spend the most time in, head over to our ultimate buyer guide on the best wetsuits for surfing for a more detailed drill-down and review of specific wetsuits models.

Whether you’re looking to surf or go for a dive in cold waters, choosing the right wetsuit is one of the most important decisions you’ll make when it comes to enjoying your time in the water! We hope this guide helps you make the right choice for you!

About the Author Thomas

I suppose you could say I came to surfing later than most. I didn't grow up by the water, but after years working the 9-5 grind I felt its draw and decided it was time to lead a slower life. These days I try and spend time in the water every day and consider the ocean as my living room: a place to relax, have fun, and just enjoy life.

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