Whites Thermal Fusion– A ScubaGadget EDITOR’S CHOICE

With the proper gear, divers can enjoy a comfortable and warm dive year-round anywhere in the world. After all, skiers dress up and comfortably ski in below freezing temp so why do divers think they can’t? Well, to be honest, before the Whites Thermal Fusion, I will admit that we sometimes had to layer and bundle to feel warm in the really cold waters. I am a cold wimp and there were times in past years that I entered the water feeling  like an over-bundled four year old on his first sledding sortie in the mid 1950s. But now, it’s a new day for temperate divers. The geniuses on the Whites design team have given us the Whites Thermal Fusion and one of the long-held dreams of most temperate water divers has come true…a REALLY WARM and REALLY FLEXIBLE dive kit.

The Tech Talk

With all the high tech fleeces available you would think it would be easy to whip up a warm and flexible suit. But, as the cliché goes, if it were easy someone would have done it years ago. There are some serious road blocks and the Whites Team has paved a new path to comfort.

Richard Myerscough (of Ocean Rodeo), former Whites co-owner and current design consultant and gave us some background on the development of the Thermal Fusion.

From the day the first Whites Fusion drysuit was tested in really cold water, the Whites design team and Fusion divers team knew they needed an ultra-warm undergarment to match the flexibility of the suit. When first released, the Fusion drysuit sold well to divers living in moderately temperate areas like southern California. In these areas, the Whites MK2 and other flexible fleece options offered reasonable warmth and flexibility. But the more northern or southern, cooler water (sub 50) divers did not jump on the bandwagon so quickly. The toasty warm Whites MK3 undergarment or other warm-enough options masked the true flexibility of the drysuit.

The pressing need for a more flexible option created a strong incentive to develop with all speed. Yet, it still took a long time for the Whites team to come up with Thermal Fusion. Why was it so hard to combine flexibility AND warmth in one undergarment? Well it is hard because, if you increase either factor in a single suit you decrease the other. More flexible – less warmth, more warmth – less flexible. It seemed like a dead end.

Along with Whites, there were (and still are) other companies that trying to build a form fitting super-flex fleece undergarment. However, there are a batch of “big buts” with form fitting hyper-stretchy suits. When a stretchy fabric stretches, it thins out, and the thinness reduces the insulation. Wetsuit divers have long been aware that the gains of super-stretch neoprene means giving up some warmth over the regular flex options. Another issue with undergarments; if you try to compensate by using extra thick fleece you loose the flex before reaching enough of an insulation factor.

If you just drop the need for form fitting, there is a seemingly simple solution . Just build a suit really loose and oversized. You can make a loose suit out of really thick fleece and a diver will swim in it (sorry for the pun) with no restrictions – think “snuggie.” But put in on under a dry suit and it can bunch in the wrong places and sag down around your ankles… another dead end.

The Whites design team became intimate with all of these limits and almost became stumped. Then Leo Luomala, of Whites R & D had a genius-dah moment. “Why not make it just like the same as Fusion drysuit?” The answer had been staring them in face. Make a ‘thermal fusion’ undergarment. Just like the Fusion drysuit, they combined an oversize inner layer with an outer compression layer. Not only did it allow for a cozy and comfortable oversize core without the sag problems; there was another subtle side effect. It is self adjusting. It will self tune to the most flexible form.

Leo used a baseball example to illustrate why this works. If you watch a baseball player just before batting they often pull up sleeve from the shoulder. He said, “try this.” If you are wearing a normal button down shirt, raise your arm over your head. Unless the shirt is oversized, you will fill the resistance caused by the material in your arm pit. But now first pull up your sleeve by gathering a little material on top of your shoulder. This time when you raise your arm you will not longer feel resistance. When you first put on the Thermal Fusion undergarment the extra material will move into a non-binding configuration and the compression layer holds it there. Plus, the extra material adds extra insulation in high heat loss areas. It also feels surprisingly less bulky than you would think.

With a design that mirrors the Fusion drysuit, it has the sexy look of a custom fit running suit but the comfort of a cozy PJs. After a dive, I hate to take it off.

Another unique feature of the Thermal Fusion is the mesh inserts that are placed under the input and dump valves to allow the flow freely.


Thermal Fusion Image

Like the Fusion drysuit, the compression layer on the TF makes every suit fit like a custom suit. For divers, this means that you need not worry about the need to purchase a new suit if you gain or lose a few pounds. For dealers, this this feature makes stocking Whites drysuits and undergarments good business. The three core sizes of the suits will fit nearly any man or woman that walks into the dive shop.


The Whites team did not depend on mere opinion to make sure this suit keeps you warm. They had the suit run through a battery of rigorous and thorough scientific testing by an independent university laboratory. The testing lab also the same testing on Whites’ competitors undergarments to make sure they had reached their goal of surpassing them all.

Late last year we tested and praised the warmth of the Fourth Element Halo undergarment. With its non-compressible mesh panels and super hero look, it is another amazing piece of warmth technology. However, because the mesh is not flexible it can only be used in certain areas on the suit; over the high heat loss areas of the body. Some flexibility is returned by segmenting the Halo suit and foregoing thickness in other areas. In general that works very well but we did notice some slight restrictions (e.g. across the chest). In the end, the Halo, while still a fine undergarment cannot match the overall flexibility of the Thermal Fusion. While the Halo is generally as warm in the core area as the Thermal Fusion, I noticed that the Thermal Fusion kept my forearms and wrists much warmer than the Halo. These comments are subtle comparisons and do not diminish our appreciation of the innovation of Fourth Element products.


After donning the Thermal Fusion undergarment in prep for my first dive, in notice I was not overheating. This comfort immediately caused me to lower my expectations. I remember clearly thinking, “well this can’t be a warm suit if I am not sweating on the surface.” But as Gomer Pyle used to say “surprise, surprise, surprise.” I completed a 50 minute dive in 48 F (8.8 C) water and all I had to think about was the beautiful surroundings. Total flexibility and comfort and not a chill.

While we are on the topic, here’s one other comment about the Fusion drysuit. We used to hear skeptical comments about how the Fusion was so light and thin, it would never hold up. After hundreds of personal dives and even more among our dive buddies, we can put that myth to rest. This suit still even looks new. Like Timex, these suits take a lick’n and keep on tick’n. Some even have experienced “urchination” (poked with urchin spikes) without leaking. And when I drove over my suit with a cart and put a couple of tiny pin-holes in the foot, it was very simple to patch – by myself, without having to send it to a shop or the manufacturer. Additionally, the SLT neck ring recently proved its worth. I tore a neck seal while prepping for a dive. In 10 minutes I had snapped a new one in place and was ready to dive. With other brands of drysuits, either incident would likely mean I would be waiting for 3 weeks on land until my suit was returned from repairs.

After over 30 combined test dives, our testers still love the Thermal Fusion. We have even tried diving with as much air evacuated as possible and were still warm in 48 F (8.8 C) water. Other test dives were in around 44 F (6.6 C) water.

There is an initiation that all divers of both the Fusion and the Thermal Fusion must pass. Leaning the unique donning technique. We have heard reps from Whites competitor try to use this to detract from the Whites line. At dive shows they say “look how they have to show or help customers put on the suit. Our suits are easy to don.”  It is a cheap hit and does not hold up. The Whites suits are very easy to don and once you learn how, you can jump in your suit as fast as any other. But if you try to skip this rite of passage you may end up in a tangled mess. A few minutes of instruction are small price to pay.

When we first started diving the Fusion drysuit, it was a conversation starter at the dive sites or on boats. Everyone would ask, “what is it?” and many were skeptical. Now it is common to find 30 to 60 percent of the divers in a group to be wearing Fusions. While the Thermal Fusion undergarment likewise draws attention, there is no skepticism. People see this suit and feel this suit and seem to immediately get it. After a few minutes they are not asking “what is it?” they are asking “where can I get it?”

The Whites Thermal Fusion is not just a great choice for Fusion drysuit divers, it should be a great paring for any drysuit. After only a few dives and even before we understood the genius behind the technology of the Thermal Fusion, we were convinced this product deserved the full five starts and our editor’s choice award.

We are grateful for help provide to us by Richard Myerscough of Ocean Rodeo, Leo Luomala, Justin Balaski, Eric Keating of Whites and Aqua Lung and the entire Whites team.

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