Hi there Vicky, and a big warm welcome to the OM forum here for you as well!Using any kind of mat will greatly increase your comfort outdoors practically everywhere upon the planet most usually, and especially so the TAR inflatable type of mats made by various outdoors kit companies now. South America then no exception to the general rule here. Well worth taking a sleeping mat with you then, for definite sure! As for whether you want to attach it to the pack outer or keep it rolled or folded within, try a few different carry variatons out maybe, to see what is right for you. I used to keep mine always on the pack outer for years, but now mostly keep it within at the back of the pack, as it offers there a bit more padding to my back in a larger sack, plus as Mike says it protects the mat a little more as well too no doubt.

Umm! South America, big place! Could you suggest for us what type of terrain you actually intend to use the mat in mostly please there at all? If you envisage using it on climbing trips where there is much rock underfoot in the base camp area then a light folding or roll kip mat might be a good idea underneath of it there too, to protect the inflatable mat base from sharp rocks/shale there, and too to increase the warmth and comfort levels a mite bit too. Always do ensure that you carry a puncture kit anyways when using those mats in the great outdoors 'in back of beyond' anywhere too though; as well as being careful not to puncture the mat at all times in its useage! You are a long way gone frm the nearest outdoors shops or kit repair places on the South American trail for sure! Are we talking here more Inca Tail, High Altiplano maybe, or lowlands then please, just out of interest?

I carry mine folded in half, tightly rolled, in its stuff-sac, inside my pack, where it can't get stuck by anything sharp. I've seen people in places like Corsica, with their Therm-a-Rests outside their packs, slinging their packs down onto the thorny maquis, then wondering why they can't get their mats inflated.

By the way... I'm selling one... click on 'classifieds' above ^^^^

Ah, well suggesting the terrain brings me to one of my issues here - I'm going all over the place, Inca trail, colca canyon, cloud forest, salt flats... Gap year trip you see! So I'm trying to work out gear that will be okey in lots of different places and climates.

I thought I would try to get a thermarest off ebay so its cheaper, or an Airic one instead, but can't decide if its better to go with an infating mat for the comfort or to avoid the risk of punctures in the middle of nowhere by getting a normal foam mat.

Do rocks and shale pose a big risk to the mats?

Thank for all your help

PS also thanks for the welcome! This site has proved very useful in the last few days.

Do rocks and shale pose a big risk to the mats?

Just avoid putting the mat on anything with sharp edges. Clear the ground of whatever you can, and if it's still a bit suspect, put something down first to take the brunt of the damage. This could be some old bit of plastic you found, or a newspaper... just use anything to spare the expensive bit of kit getting damaged.

I once saw someone sitting on a Therm-a-Rest while popping the blisters on his feet with a needle. In between each blister, while he applied moleskin, guess where he stuck the needle???

Awesome. I'll go check those out Trevor, thanks.

and I'm afraid I'm a weight-counter Paddy, so if I get one it'll probably be a prolite not a classic, but thanks anyway.