I am looking at doing an extended trekking/climbing trip for 4-5 months through Patagonia and the Andes and I will be travelling with a lot of gear to numerous different locations. I am just curious from those of you that have done big mountaineering/climbing trips before, do I need some sort of insurance in case my gear gets damaged/stolen. I'm not so worried about it while on the plane, it's more the months while I'm on the road.

If it's needed, any recommendation on where to find it?

Ask a travel agent, they usually have brochures from a number of insurance companies that issue travel insurance policies. But read the brochures carefully, as some don't cover you for mountaineering-type activities (using ropes, crampons, etc), while some will only cover for trekking-type trips (trail hiking). Most can also supply you with a list of recommended hospitals in the area(s) where you'll be traveling. Also note that you are usually required to pay for any medical services you need up front and the company re-imburses you once you file a claim (typically when you return).

No regular travel insurance will cover you for any loss if you are involved in mountaineering or rock climbing. This will include your equipment, not just medevac for an injury. You can say you're trekking, because that is covered by nearly every policy, but if you try to claim a few thousand bucks of stolen climbing hardware then they will notice it and reject it.

Some will have extensions you can pay for that might cover rock climbing (and skiing).

If you think it's worth covering properly, get a policy through the American Alpine Club or Austrian Alpine Club (UK) as they are specialist policies that cover climbing. Maybe the ACC has similar?

There are a few mainstream insurers that will cover it for extra, maybe try Travelguard or similar. If you are Canadian, there will be potentially major differences in the prices you will pay compared to Americans.