Review: Merrell All Out Blaze Ventilator Waterproof

The Merrell All Out Blaze Vent WP

When selecting a pair of new shoes, the so-called 'ground feel' and foot flexibility of a pair of shoes is extremely important to me as I come from a minimalist running background. Because of this, I shy away from heavy hiking boots, and only consider them when needing to carry a heavy backpack for multi-day hikes. Merrell's All Out range is known for their lightweight and flexible features. This, and the fact that I have really enjoyed using the Merrell All Out Crush for trail runs, convinced me to try out their waterproof hiking equivalent—the low-cut version of the Merrell All Out Blaze Ventilator Waterproof.

Material & Features

The All Out Blaze Ventilation hiking shoe attempts to retain the classic characteristic of the All Out by providing protection without inhibiting movement, whilst still keeping it both ventilated and waterproof; something that manufacturers have struggled with since time immemorial. The main features of these shoes are:

Waterproof leather and mesh upper – This combination keeps the outside of the shoe waterproof and breathable by incorporating M-Select DRY technology. It utilises a type of fabric that prevents water from passing into the shoe from the outside whilst also allowing moisture that is generated by the process of sweating to escape from the inside. The leather elements also increase the durability of the shoe.

Soft E-Foam Midsole - The midsole provides plenty of shock absorption and helps to cushion and protect the feet from impact when going over exposed trail elements such as rocks and roots.

Vibram® TC5+ rubber outsole - The outsole is made from Vibram's TC5+ rubber, giving it excellent traction for a variety of terrain. The outsole has a lug depth of 5mm to improve grip and the traction-giving lugs themselves have been hollowed out in an attempt to reduce some of the weight.

The Review

Numerous articles and studies over the years have examined both the advantages and disadvantages of different types of foot strikes when running, and take into consideration factors such as efficiency, braking force, and how impact is absorbed by the body. This debate has been going on for a long while now and nothing overwhelmingly conclusive has ever emerged. I personally do not think that there is a specific stride that all hikers and runners should adopt, but rather, I think that the stride one chooses is heavily dependent on one's physiological makeup. I am a forefoot striker and have been running that way before I learnt about the differences between the strikes, and well before I was aware that forefoot striking was my natural gait. This also helps explain why I have always been drawn to minimalist running and tend to balk when seeing shoes with heavy protection.

Toe Cap

With that being said, one measurement that is obviously very important for me personally is the 'heel-to-toe' drop of the shoe, which is basically the difference between how high the front and back of one's foot is above the ground when it sits in the shoe. Shoes that have a conventional heel-to-toe drop (approximately 10-12mm), will tilt your foot forward because of the high heel, thus encouraging heel striking. Consequently, the closer the 'heel-to-toe' measurement of a shoe gets to zero, the more flat one's foot will be. The Merrell All Out Blaze Vent WP has a 15mm heel cushion and a 9mm forefoot cushion, giving a drop of only 6mm, well below the conventional number.

One fact that remains incontroversial, however, is the almost five-fold increase in energy requirements when the same weight is borne on the feet instead of the torso. The study that is most often refered to is the one that was conducted by Soule and Goldman way back in 1969. The study found that the energy requirements increased by a factor of 4.7 to 6.3 depending on the speed, which translates to an additional 1% for each 100g carried on the feet. Despite the bulky-looking outsole, the weight of the Merrell All Out Blaze Ventilator shoes (760g for the pair) is fairly low for low-cut hiking shoes. Merrell achieves this low weight by not only carefully choosing the material that they use, but by also incorporating small but fairly significant features such as their hollowed-out lugs. The weight is so low that I really wouldn't think twice about the shoes if I had to break out into a run whilst I was wearing them.


Hollowed-out Lugs

I tested the shoes on several hikes in three different countries, which exposed them to a fairly wide variety of terrain, weather, and temperature ranges. The first hike that I tested them on was a two-day hike up to the summit of Mount Tok Nenek in Malaysia (not the Yong Yap-Bubu loop). This hike is known to be extremely wet as it involves a large number of river crossings; at least a dozen or so before even the first campsite is reached. Before I even began the hike, however, I had an inkling that the shoes would not hold up very well in those conditions, but was compelled to test them anyway due to the 'waterproof' and 'ventilator' tags in the name. The shoes did well to prevent rainwater from entering but were also slow in allowing my sweat to dissipate out (I initially thought that this was most likely due to the humidity). When it came to the river crossings, I found that I had been way too optimistic for having thought that the shoes would be able to vent out the water after being completely submerged (the way the drainage ports on the sides of the All Out Crush would have). But once again, I was reminded that the high humidity of the tropical forest has a stubborn tendency to keep things that are wet from ever drying out.

Heel counter & Pull-tab

The shoes performed fairly well on the other two hikes, however, primarily because no river crossings were required. The hike up to the Galties in Ireland involved walking through small puddles (the puddles were frozen over in Finland), boggy areas, and sections of long grass that were covered with dew. Despite all this, the shoes kept my feet dry, warm, and rather snug, or at least they did early on. However, during the later part of the hike, I found that the sweat had begun to build up. Because both hikes were in locations that were not humid—Finland and Ireland—I had expected the sweat to dissipate rather easily and was fairly surprised to find that this was not the case. The grip was very good nonetheless. The rubber outsole worked well on rocks as there was sufficient flex to allow it to wrap around the rock a little bit more than stiffer hiking boots normally would, yet it was also firm enough to allow me to edge off small footholds. I go by my own maxim, "Traction maketh a shoe", and in that sense the Merrell All Out Blaze Ventilator didn't let me down.


• Decent waterproofing

• Fairly light for hiking shoes

• Low heel-to-toe drop, good for forefoot strikers

• Small breaking-in period

• Good traction with an outsole that can suit a variety of terrain

Pro / Cons

• Seems to be neither here nor there, a jack-of-all-trades but master of none


• Ventilation is not up to par

• Low heel-to-toe drop, bad for heel strikers

The Take-away

If you are looking for an all-round pair of lightweight hiking shoes that are comfortable yet will still keep you dry in the rain, then these might just be the shoes for you. These shoes are light enough to take a short run in and have good traction that can tackle all kinds of terrain. If you need good ventilation, however, you may just need to resort to getting a pair of non-waterproof, vented shoes.

Merrell Outlets


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* Footwear for this review was supplied by Merrell Malaysia *