3RD ROCK Mercury Jean Review




3RD ROCK is a UK (Derbyshire) based sustainable activewear brand with a strong ethical and environmental ethos. Founded back in 2010 by Jessica Mor who is both a climber and fashion designer 3RD ROCK aims:

“To design and create the best, most comfortable & long-lasting products, while causing no unnecessary harm.”

To this end the Mercury Jeans are made using organic cotton. Now while there may be a bit of a backlash against organic foods as being overpriced and nutritionally no better than most other foods in some circles what people often forget is the farming process. Organic farming exposes the farmers and workers to little or no toxins by way of pesticides (up to 77 million cotton workers suffer poisoning from pesticides each year http://www.cottonedon.org). These same toxins end up contaminating water via runoff   compromising drinking water supplies. So organic cotton is basically a ‘good thing’. Keeping with their ethical stance and belief in traceability 3RD ROCK clothing is all manufactured in factories that follow the ethical trading initiative (ETI) the Mercury Jeans originating from Turkey. The organic cotton fabric that 3RD ROCK use has a slight stretch to it through the addition of 3% elastane which enhances mobility and is super soft. So much so that to begin with I was worried that they might not withstand close interaction with the local gritstone. Jamie kindly sent out a small and a medium so I could get a good fit for my alpinist/cyclist thighs and fit wise I ended up with the medium. The small fitted my 30″ waist perfectly but was a little too ‘hipster’ snug on the quads so I opted for the medium – if you’re larger that average in the quads you may need to go up a size and factor in a belt when fitting the Mercury Jeans. So what makes these a climbing or technical jean? Well there’s the ubiquitous diamond cut crutch to aid those boxer splits (in my dreams!), the legs have a clever series of ‘darts’ to give a slight pre-bend on the knee that helps avoid snagging allowing the trouser legs to slide effortlessly and there is a double layer of fabric on the front of the leg running from the knee to mid thigh – right where that crafty knee bar is likely to wear through.

There are other nice design touches throughout – I especially like the humorous word play on the fly label 🙂 It’s good to see a British company doing well in the ethical/environmental climbing clothing market.

In Use
I’ve put the Mercury Jeans through their paces for nearly three months now on the local grit and indoors at the Depot. The weight is a good compromise I’ve not found them too warm indoors and they have been fine down to 7 or 8°C out on the grit.

Green Traverse Shipley Glen – Baron Jules questioning if the left foot is out of bounds 🙂

The cut has proved excellent in terms of mobility, there is no sense of the fabric ‘dragging’ or restricting movement on high steps or wide bridging moves. The only down side is that I need to wear a belt. Durability wise my initial fears that the fabric was just a bit too soft have proved unfounded – the Mercury Jeans look as good as new and although I’ve not been thrutching up any offwidths there’s a scattering of knee bars (and the odd ‘alpine knee’ top out) on the local problems and so far no holes in the legs. Overall they are the sort of jeans you can drive to the crag, get your session in and then stop off for a beer or coffee and not feel out of place in the bar or cafe. I’ve got the ‘Night’ (bluey green) colour that has a sort of euro spring summer vibe to my mind – if you prefer the more restrained go for the black or ‘lizard’.


  • Unrestricted movement
  • Build quality
  • Environmental/ethical practice


  • Size for size snug thighs – but check out the Strider for a wider leg option.

SRP £75.99


RiCGR_RichMugchie is the enthusiastic amateur of the team. Enjoying all aspects of climbing but especially alpine, winter and his local grit . Having managed to survive the vagaries of both fluorescent Koflachs and rainbow tights in the 80s he looks forward to an even more stylish future. A shady past in mountain marathons and adventure races, including the Marathon des Sables, means he’s an advocate of fast and light. Though the former is debatable if you’ve seen him on a tricky lead!

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