At io we’ve always been about going natural. And now it’s time to go ‘au naturel’ by going io natural in our first ever, and possibly the world’s first ever, Nude Ultra. No synthetics. No harmful microplastics. No landfill. No nothing. Do it for the planet people!

Where will this event be held?
We’re just awaiting final approval for courses across Australia but the locations will be Sausage Gully (Victoria), The Butt (Tasmania), Flirtation Hill (NSW), Fanny Creek (NT), Yorkey’s Knob (Qld) and Cockburn (SA).

What distances will there be?
You can choose from 10km, 25km, 50km or the Full Monty 100km. Shoes and (natural merino) socks allowed. Or enter the Birthday Suit Barefoot Ultra and wear literally nothing at all. It’s up to you.

Is there a mandatory gear list?
No, we’ll have a list of things that are mandatory to not have. And it’s clothes. Because it’s a Nude Ultra. So no synthetics. This event is all about keeping it natural. (Hydration devices allowed. If you want to take a collapsible cup to refill at the support stations, where you store that is up to you.)

If ioMerino is natural, why can’t I run in that?
Because this event would be nowhere near as legendary if it was a Nude Ultra where you actually wore clothes. But yes, absolutely, io is the way to go if you want to keep things natural. 

Are there support stations along the way?
There will be support stations approximately every 5kms offering water, Tailwind, gels, chips, lollies, sunscreen and anti-chafe creams.

Isn’t a nudie run illegal?
Probably. But hey, live a little.

Could running natural cause some sort of injury?
We expect all runners to run within their own abilities and body types.

Is this a body positive/inclusive event?
You bet your bottom it is. You can be any size from XS to XXXL and beyond. We don’t care how you look, we care that you’re awesome. And if you got this far in these FAQs, you’re definitely awesome.

Is this all some sort of stupid April Fool’s joke?
Yes. Yes it is. If you really like the idea of ditching the stinky synthetics and keeping things natural, just go with io.


Fabric Guide

While Merino is an amazing natural fibre, not all Merino fabrics are created equal. At ioMerino, we make our own fabrics, using only the best quality fibres, and to very specific specifications that make the most of the natural benefits of Merino. All of them are 'Merino rich’. No cheap blends passed off as Merino. No cheaper scratchy fibres or synthetic substitutes to save money. No unethical production. And each fabric is made for a specific purpose. So if you see something with a small amount of elastase or nylon added, you can be sure it absolutely needs to be there to enhance the natural stretch and durability. 

It took every bit of our 140 years of experience in the wool industry to perfect our fabrics, but we think you’ll agree the end result was more than worth the effort.

Ethically Made. Ethically Sourced. Perfectly Natural. 


Altitude / Zodiac

Lightweight 170gsm 96% Australian Merino Wool with 4% elastane for extra stretch and comfort. A MicroMerino® Fabric. 


Ultra / Universal

Lightweight 160gsm 83% Australian Merino Wool blended with 12% nylon blended for extra durability and 5% Elastane for stretch and comfort.



Midweight 265gsm 96% Australian Merino Wool with 4% elastane for extra stretch and comfort. A MicroMerino® Fabric. 


Summerino - Celsius 

Made from 45% ultra fine MERINO (Ultra Lightweight 150gsm), 45% natural TENCEL (made from sustainably grown wood fiber), and 10% nylon for extra durability. 


Summerino - Keystone 

Ultra Lightweight 150gsm 100% Australian Merino Wool. A MicroMerino® Fabric. 


Merino Compression

Midweight 280gsm 76% Australian Merino Wool, 15% Elastane and 9% Nylon for extra stretch and compression properties.



Ultra lightweight ribbed 155gsm 100% Australian Merino Wool. A MicroMerino®  Fabric. 



Outer Weight 280gsm Fleece 100% Australian Merino Wool. MicroMerino®  Fabric. 



Midweight 260gsm 100% Australian Merino Wool. A MicroMerino®  Fabric. 



Midweight 260gsm waffle texture 100% Australian Merino Wool. A MicroMerino®  Fabric. 


Stride / Glacier / Velocity

Midweight 255gsm French Terry 100% Australian Merino Wool. A MicroMerino®  Fabric. 


Natural Merino Wool benefits: