Lunasurf 4mm Surf Boot Yamamoto Cold Water Wetsuit boots
Stay warm. Surf longer.
The Lunasurf 4mm Yamamoto Surf Boot is made from 100% Yamamoto neoprene — warmer and more durable than standard neoprene — keeping your feet warm and your surfing sharp in the coldest conditions.
Features
- 100% Yamamoto neoprene — warmer and more durable than standard neoprene
- 4mm thickness for cold water
- Grippy sole for traction on your board and on rocks
- Comfortable fit that doesn't restrict movement
- Tested in some of the world's coldest surf spots — Iceland, Scotland, Norway
Trusted by Lunasurf ambassadors in the world's coldest waters.
Lunasurf 4mm Yamamoto Wetsuit Boots
Premium Cold Water Performance Without Compromise
Not every cold water session demands maximum thickness.
The Lunasurf 4mm Wetsuit Boots are built for riders who want exceptional warmth, unrestricted flexibility, and the confidence to stay in the water longer. Constructed from 100% Yamamoto #39 Japanese limestone neoprene, they deliver premium insulation without the bulk of traditional cold water boots.
Whether you're surfing, kitesurfing, wing foiling, windsurfing, SUP, or river surfing, the 4mm offers the perfect balance of warmth, comfort, and performance.
Built with 100% Yamamoto #39 Limestone Neoprene
The material beneath your feet matters just as much as the wetsuit around the rest of your body.
That's why every Lunasurf boot is made entirely from 100% Yamamoto #39 Japanese limestone neoprene—one of the world's highest-performing neoprene materials.
Compared to traditional petroleum neoprene, Yamamoto #39:
- Retains significantly more body heat
- Absorbs virtually no water
- Remains lightweight throughout your session
- Stays soft and flexible in cold conditions
- Resists compression for longer-lasting performance
The result is a boot that feels lighter, stays warmer, and performs consistently from your first paddle to your last wave.
Engineered for Real Cold Water
Every detail has been designed with cold water sessions in mind.
✔ High-top design for extra ankle coverage and a secure overlap with your wetsuit.
✔ Wide reinforced Velcro® strap keeps the boot firmly locked to your foot without loosening during your session.
✔ Durable high-grip sole provides confident footing across slippery rocks, reefs, riverbanks, and long walk-ins.
✔ Quick ankle pull loop makes getting your boots on and off easier, even with cold hands.
✔ Plush recycled thermal lining traps warmth, dries quickly between sessions, and feels soft against your skin.
✔ Silky smooth outer jersey maximises stretch and flexibility for a natural feel.
From the shoreline to your last wave, every feature has been developed to perform in demanding cold water environments.
Who Are the 4mm Boots For?
The 4mm is Lunasurf's most versatile cold water boot.
Exactly when you'll use it depends on where you ride and how tolerant you are to the cold.
Ideal for:
- Spring and autumn throughout the UK and Ireland
- Winter in milder climates including France, Spain and Portugal
- Summer and shoulder seasons in colder regions such as Scotland, Norway and Iceland
- Year-round use in many cool water destinations around the world
Perfect for:
- Surfing
- Kitesurfing
- Wing Foiling
- Windsurfing
- SUP
- River Surfing
If your conditions vary throughout the year, the 4mm is the boot you'll reach for most often.
Warm Feet. Better Sessions.
Cold feet don't just affect comfort.
They reduce concentration, drain energy, and often bring a great session to an early finish.
Keeping your feet warm helps your whole body stay comfortable, allowing you to focus on the conditions rather than the cold.
When your feet stay warm, you stay out longer.
4mm or 8mm?
Choose the 4mm if you normally ride in water temperatures between 7°C and 13°C, or you're looking for the best balance of warmth, flexibility, and board feel.
Choose the 8mm if you regularly ride in water below 8°C, spend long periods in freezing conditions, or simply know you feel the cold quickly.
Many Lunasurf riders own both—the 4mm for spring, autumn, and milder winters, and the 8mm when winter really arrives.
Proven in Some of the World's Coldest Waters
Lunasurf boots aren't designed in a warm office and tested once.
They're worn and trusted in the cold waters of Scotland, Norway, Iceland, and beyond by riders who expect their equipment to perform when conditions are at their best—and often at their coldest.
Complete Your Cold Water System
Pair your 4mm boots with a Lunasurf Yamamoto wetsuit, gloves or mitts, and hood for complete cold water protection.
Keeping your extremities warm makes a remarkable difference to comfort, performance, and how long you can stay in the water.
Premium Materials. Premium Performance.
The best cold water sessions are often the ones most people never experience.
The Lunasurf 4mm Yamamoto Wetsuit Boots are built to help you enjoy them in comfort, with the warmth, flexibility, and performance that only 100% Yamamoto #39 limestone neoprene can deliver.
Shop the Lunasurf 4mm Yamamoto Wetsuit Boots and experience the difference premium materials make.
Pairs well with
Lunasurf 4mm Surf Boot Yamamoto Cold Water Wetsuit boots
If you have any questions, you are always welcome to contact us. We'll get back to you as soon as possible, within 24 hours on weekdays.
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Shipping Information
All wetsuits have FREE shipping worldwide.- All orders over £100 FREE shipping within the UK.
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Contact Us
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Taxes & Duties
All prices shown are excluding VAT. UK customers will have VAT added at the checkout for the EU and the rest of the world you will pay you local VAT upon import.
Wetsuit Boots Features In Detail
ECO Friendly Recycled Thermal Lining.
Quick drying, comfy, thermal, silky smooth recycled linings makes for a snug, warm, lightweight, high performance wetsuit. We believe that to make a great wetsuit you need the best eco aware materials.
Quick Dry Lining
Glued & Blind Stitched (GBS)
Every seam has been glued and blind-stitched to reduce water entry and have excellent durability. Seams and panels have be strategically designed with flexibility and mobility as the focus Making for a non restricting comfortable wetsuit.
4-Way Stretch Tape
A thin comfortable 4-way high stretch neoprene tape. Placed on all interior seams minimising water entry and maximising warmth retention.
Tech Specs
Yamamoto #39
Super Light Weight ECO friendly Non-Petroleum based Japanese limestone neoprene with the perfect balance between warmth, stretch and durability.
Rubber made from the purest Japanese limestone.
The limestone that YAMAMOTO use is sourced from Mt. Kurohime, which stores billion tons of the purest Japanese limestone. Out of such purest limestone, YAMAMOTO only uses the highest-grade limestone, containing 99.7% of calcium carbonate.
Nitrogen Gas Infused Closed Cell
The closed cells are packed together at an extremely high density and each individual cell is filled with nitrogen gas to prevent water penetration and increase heat retention. The nitrogen closed cell content is over 93% — over 30% higher than most competing materials — and with virtually no water absorption means the weight of this rubber remains nearly identical in wet or dry conditions, giving you more warmth than thicker wetsuits without the weight.
Honeycomb Structure
Yamamoto Corporation’s neoprene rubber is classified as (CR) “chloroprene rubber.” The special rubber incorporates an independent closed cell structure which adds high functionality including super light weight, high heat‐retention with good flexibility neoprene.
Sustainability
Our mission, create Affordable, Durable ECO friendly wetsuits.
Canola Oil
Although certain amount of oil is needed to make soft rubber foam, YAMAMOTO stopped using petroleum-derived oil.Instead, YAMAMOTO uses food-grade pure Canola oil, which is widely used as Tempura oil in Japan for sustainability and safety.
Renewable Energy.
Petroleum Oil
Is expected to be depleted in next 50 years. Limestone, on the other hand, can be utilized for a wetsuit material semi-permanently.
Renewable Energy Sources
When making CR from limestone, it requires a lot of energy. To reduce environmental impact, most of the energy used comes from renewable energy sources such as hydroelectricity.
Longer Product Lifetime
As CR is excellent at performance such as weather resistance, CR wetsuits last longer.
One of the most eco-friendly ways to achieve sustainability is to use one product for a longer time in order to facilitate that the product has to last longer.
Ocean Polution
Our beautiful blue sea is now in danger of being covered by marine debris.
It is estimated that there are 150 million tons of plastic waste in the ocean and at least 8 million tons are flowing in the ocean annually. Reference: WWF Japan WEB site "About marine plastic problems"
YAMAMOTO is working on recycled jersey materials to reduce pollution of the ocean and to let more people to be aware of this issue. It is estimated that the number of marina debris is going to exceeds the one of fish in 2050.
YAMAMOTO will continue to work on solutions to conserve our beautiful ocean.
FAQs
Please read our FAQs page to find out more.
Do wetsuits stretch with use?
When you are first trying it on dry it is important to understand that once a wetsuit has been used a few times it will loosen up and feel more comfortable. With use the wetsuit will stretch to your body becoming form fitting.
What countries do you ship to?
We offer FREE standard shipping worldwide on all wetsuits. You will also have the option to upgrade to premium DHL paid service for an express delivery.
Do you offer a warrantee on your wetsuit boots?
Yes we offer a 12 month warranty on materials and manufacturing, We do not cover misuse, fin cuts or any damage caused by hitting the reef.
How do I care for my wetsuit Boots?
Wash it out with clean, cold water after every surf. Hang dry, don't dry it out in direct sunlight, Don't machine wash/dry, Don't use detergents.
Can I return my wetsuit boots?
Yes providing that the wetsuit boots have NOT been used or damaged. You are welcome to swap sizes if you didn't get it right first time. Return postage is your responsibility
How do wetsuit boots work?
Lunasurf Wetsuit Boots are awesome things, with today’s technology we can stay warm and have fun in the coldest of conditions. You can feel light, loose and warm unlike the wetsuits of yesteryear. Our wetsuits are 100% made using only the best Yamamoto Japanese limestone based neoprene's. That are then lined with a water/wind repelling buttery, stretchy lining that insulates you from the cold water water, air temps and winds. Your Wetsuit is made up of panels of Neoprene. Wetsuits are not designed to keep you entirely dry. A small amount of water gets trapped between your body and the neoprene. Your body temperature then heats up this small amount of water giving you a nice warm feeling. This is why finding the correct fitting Wetsuit is absolutely essential. Heat does eventually escape through the neoprene but very much like clothing the thicker the Neoprene the warmer you will be.