The Thermal Helix version is astoundingly stretchy. Distinctive chest and torso panels made of flexible 5mm Yamamoto Aerodome neoprene help to maintain an efficient body position in the water. Straight from the first try the suit felt super comfortable and equivalent to the thinner standard Helix.

Little details on the inside of the back zipper. The full internal orange zirconium material is clearly visible. It is a pretty comfortable material that essentially feels like wool on the skin. It helps to decrease water absorption and shields against heat loss. Moreover a diminutive hook assists to securely store your keys while training.

The 1mm slim neoprene used on the arms feels particularly good and, despite the added insolation they create an unspoiled feeling for the water and a great sense whilst gliding. The pictured aqua-sell cuffs made out of extra flexible silicon stops H2O from entering the suit without being too close fitting.

One-piece 1.5 neoprene sections throughout the shoulder parts permits full movement.

Another look at the cozy inside of the Thermal Helix.

Attention to detail can be witnessed throughout the suit. The blueseventy designers made sure that the stitching and location of the neoprene stickers are spotless.

A vital slice of the Thermal offering are the neoprene socks. Previously I had certain cruel incidents with neoprene socks, but the blueseventy Thermal ones sheltered the feet in a perfect manner. The Zirconium liner isolation and the actual length of the socks benefit the user.

A good feeling for the water is vital. Where as many swim gloves merely helped the isolation of the hand, the Thermal Swim Glove surprised with a great fit and a sensation for the water. The extra long cuff works perfect with the arms and makes sure that water does not enter the suit.

In addition to the insulation gear blueseventy bids the award winning Hydra-Vision goggle. The soft frame produces a pleasant and safe fit even while swimming in choppy waters. The highlight though are the polarized lenses that offer a remarkable eyesight that can be highly beneficial while swimming outdoors throughout all the seasons.

When asked about the development of the thermal collection, blueseventy brand and product manager Mike Orton said: “We analyzed what the dive and surf industries do for cold-water adventures and we pushed our manufacturing team to establish new ways to glue, stitch and tape."

The manufacturer states that the suit is fit to use till a lowest temperature of 48ºF or 8.5ºC. We tested the products throughout lake and longer swims in the Baltic Sea with temperatures as low as 44.24ºF or 6.8 ºC. At all times the suit helped to stay warm, even though we just wore swim shorts and no other additional clothing under the suit.

A suitable head shield is fundamental during chilly excursions. The Thermal Skull Cap is similar to a standard cap but with additional wool liner inside. Soft and flexible neoprene makes this cap easy to use. Even though there was no lube used in testing, chafing was not a problem.

Straight from the first use it did not feel different to swim with a suit that has additional insulation. Even though there is extra material included this does not affect the flexibility, fit and the buoyancy. Unquestionably it benefits to extend the desires of open water swimming and supports swimmers that have their struggles with frostier temperatures.

Undoubtedly it will take a bit longer until you want to stop your outdoor swimming session with the blueseventy Thermal range.