A good baselayer

polypropylene. its not a perfect world... get a raincoat with vents on it, pit zips, core zips, vented pockets to minimise heat buildup... and not the macpac prophet, it's heavy and you'll still sweat to death in it

Use a soft shell jacket.

I've never found one base layer that does everything perfectly. However, for years I have used a combination of two: 'dry-max lite' base layers from Huntech, with an optional polyprop to go over the top. Dry-max lite was by far: - Best single layer I've found for keeping cool - used alone the air mesh allows circulation of air and great cooling - Used alone effectively wicks moisture from skin to surface of cloth - Used under goretex / polyprop effectively moves moisture away from skin to the outer layer, keeping skin dry and allowing that layer to dispose of the moisture - Holds very little moisture so even when wet (e.g. after swimming rivers) dries very quickly - in under 30 mins when worn, and always overnight in hut even without a fire. - Does not get smelly (unlike polyprop) - Quick drying means I generally wash (rinse) them every night to remove sweat/salt buildup Unfortunately Huntech have closed so I'm looking out for a suitable replacement. The dry-max lite looks like the airmesh running tops many sports people use, but is much thinner/lighter, and unlike them does not ladder (go for a day's bush-bashing in a running top from R&R sport, etc and you'll see what I mean) . Stony Creek have something similar, but only in long-sleeve - I guess I may have to buy one and modify ... unless anyone else knows of other manufacturers of s short-sleeved, hi-viz equivalent.

You do understand that Gore-Tex only kicks in and works at certain temps right so I doesn't seem to breath and work very well. The best set up for warmer temps I believe is a single thermal top a soft shell top and a light weight water proof outer layer. If is is rainy you are going to get wet, there is no way around it. Also if you are walking up hill and its muggy you are going to sweat.

gore tex only really kicks in once the humidity level inside the jacket is already very high.... it works better in lower temps and lower outside air humidity

I wear Russell Athletic knit style polyester L/S sport tops as a day to day baselayer. I buy them from Amazon US, they cost about $10-20 each and use USshop to get around the export restrictions. They work really well because they keep me warm with a degree of breathability. I buy them from the US so I can get bigger sizes, the XXL I wear would be the same as a NZ 3-4XL. I only use my Merino top when it is really cold, i just get too hot otherwise. I use a blend of sports/hunting/tramping clothing, you should check out some of the sports and hunting websites for gear, not just Macpac/Bivouac/RnR etc.

I wear either Stoney Creek, Mountain Design Zuma, or Adidas Climatech polos, depending on duration or type of trip. I like that they have collars. They're breathable, heat venting, & sweat wickable. They have anti-stink treatment, but are easily wash & wear fabrics. They're so comfortable to travel in, they're never a concern. Next layer is a full-length zip, sleevless, light nylon cycle top. it immediately cuts wind & traps heat, without adding bulk. If you have to go to coats or light merino, then you're starting to negate the base layer anyways.

@proactive - the climatech sounds like a similar fabric to the huntech drimax-lite I'm trying to replace. Does it stand up ok to bush-bashing? Or does it ladder? Not keen on the 'ravaged by a pack of tigers' look - have plenty of clothes that look like that!

@ madpom. Nah !. The Adidas is basically a runners polo. I wear it on club one-day hikes. Recommend the Stoney Creek polo. Any good hunting shop has them. Even CRT farming shops. Probably cheaper than tramp-wear if you watch the sales ? A simple "Google'' will bring it up. Like "Bradley1", I like to shop at Hunting & Fishing, & CRT time to time. Also the Protector Safety & industrial suppliers Cycle shops are worth a look too, but usually the most expensive option (unless you go Torpedo 7). There seems to be a bit of brand snobbery associated with tramping labels. Suspect the original poster was wearing a Macpac Mountain Tee. Immediately, those things add a couple of degrees heat, & they're hopeless for snagging & pilling. Got half a dozen 2XL I might wear in winter.