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Reviewed: Synergy Endorphin Thermal Wetsuit

Synergy once again defies all pricing structures with the Endorphin Thermal by creating a well-performing cold-water wetsuit that costs substantially less than its competitors.

Review Rating


An award winning wetsuit mimicking, if not mocking premium brand models on their flexibility and speed in a thermal model with a price to quality ratio that is unquestionable. The Synergy Endorphin will have you doubting every over-the-top wetsuit purchase you have ever made.


Flexible every which way

Light weight and silky smooth interior

Price tag of $400? Yes please!

Transition without any hang ups


Rear neck velcro and zipper not positioned spot-on for best overall comfort

Extra effort required to adjust for sighting

Not as a buoyant to aide the inexperienced swimmer





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Synergy Endorphin Thermal Wetsuit: The Basics

The Endorphin is designed as a mid- to high-level wetsuit utilizing the higher quality grades of Yamamoto neoprene with a thermal liner. It is suitable for a wide range of swimmers, leaning more toward the avid open-water veteran. It comes in nine different sizes for the thermal version. With superb functionality (or advertised 680% flexibility; who is doing that math?) and a smooth interior thermal liner, look to use this wetsuit more often in the average-weather race rather than drag it through the elements on the weekend group swim.

A man wears the Synergy Endorphin Thermal Wetsuit for a review.
(Photo: Synergy)

Synergy Endorphin Thermal Wetsuit: What We Loved

The Endorphin’s ease of swimming functionality is instantly a highlight at first use. As Larry David would say: “It’s pretty, pretty, pretty good.” The wetsuit required no break in time and felt race ready right away. Those with lengthy strokes; those who appreciate unrestricted movement; and those who like to turn up the tempo are going to appreciate the speed and range of motion of this wetsuit. It is all due to the vast use of 2mm neoprene in the arms and shoulders. As it is a thermal-focused wetsuit with a liner, don’t expect it to be a good choice over 70 degrees.

Despite testing it in 52F water, this user felt appropriate, yet fair heat retention from the wetsuit. Perhaps slightly cold feet, but otherwise warm where it was needed. One other attribute that stood out was the wetsuit’s side-to-side balance. Five millimeter neoprene is utilized but not so much in excess that the body struggles to rotate or sits abnormally high in the water. And finally, the best part: this wetsuit is sold at an extremely fair price of $400. It could easily pass as a premium model, and the reality is you won’t be able to find a decent thermal wetsuit at this price anywhere.

Synergy Endorphin Thermal Wetsuit: What We Didn’t Love

The pandemic has left its mark on all of us in some way, shape, or form. This user definitely noticed a change in shape. Some of it around the waist from too much holiday eating and birthday cake (oh the joy of turning 40), and some from regained muscle mass. Turns out daily push ups can keep a person looking sexy when pools are not readily available. Regardless, at almost six feet in height and a bump in weight from 160 lbs to 170lbs, the M2 (medium-tall build) seemed like the logical size choice. But the M1 (medium) was recommended. On drylands, the M1 felt like a suitable fit. In the water, the torso was spacier than expected despite this user’s extra cushion.

We did get some water in the wetsuit towards the end, but it should be noted that triathlon racing apparel was not worn during the test. That extra layer could have easily filled the space. Additionally, with a fully zipped neckline, there was a lump-like pressure from the neoprene on the back of the neck. The zipper is a standard design found on all models, but its final resting place—in conjunction with the neckline velcro strapped down—was bothersome, especially when sighting. With some (not a lot) of 5mm neoprene at the waist and the uncomfortable rear neckline lump, it took extra effort to sight buoys and beach. At the end of the test, this tester wondered if even the S3 (small-tall) would have been a better fit.


The Synergy Endorphin Thermal is a competitive wetsuit that cold-water swimmers should love. With new swimmers and a fast learning curve, there is the potential to quickly fall in love with the Endorphin. But those needing more time to prepare for the variable conditions of open water should test beginner models with more buoyancy. Synergy offers a 30-day money back guarantee if you are not satisfied with the product. Regardless of the buyer, this is one of the best functional wetsuits on the market at an absurdly low price—especially given the thermal liner. That said, be sure to temper your expectations on durability. Get around this shortcoming with better wetsuit care. It takes extra attention to be gentler with finer neoprene, but ultimately it translates to a longer lifespan and less repairs. But should an accident happen, Synergy has the buyer covered with a two-year warranty.

Finally, for better or worse, we have all experienced physical changes in some form during the pandemic. Perhaps this is a good reminder for buyers to do a self-check on measurements so you can get the right size for optimal performance.

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