The O Circuit is the full-strength version of Torres del Paine: a 120 to 135-kilometre loop around the entire Paine massif that adds the park’s wild back side — the Dickson, Perros and Grey glaciers, and the infamous John Gardner Pass — to everything the famous W trek covers. It takes 8 to 10 days, and it is widely considered one of the great hut-and-campsite treks on earth. The catch is the booking system, which is genuinely confusing and punishes late planners. Get the admin right and the walking is the reward.
The circuit is walked counter-clockwise, starting at the Central sector (by the park entrance near Laguna Amarga), looping around the back of the massif, and rejoining the W route at Paine Grande before finishing at the towers viewpoint. You walk it with everything you need — the back side has no resupply — but water is plentiful and famously clean straight from the streams.
The booking puzzle
This is the section to read twice. Accommodation on the circuit is run by two separate companies — Vertice and Las Torres (formerly Fantastico Sur) — with different booking sites, different release dates and different prices. Booking windows typically open between April and June for the following season and the popular dates sell out fast; when bookings open is announced first on trekking forums and the park’s social channels. As a rough guide, recent trekkers paid around US$11 per person per night at Vertice campsites and around US$40 at Las Torres campsites (bringing all their own gear), with refugio beds and full-board options costing several times more — and prices rise every year. The old free CONAF campsites are closed, so there is no budget loophole. You must also buy your park entrance ticket online before arriving (tickets are no longer sold at the gate): the multi-day pass for adults is around US$49.
The route
A standard 8-day shape: Central to Seron, Seron to Dickson, Dickson to Los Perros, Los Perros over the John Gardner Pass to Grey, Grey to Paine Grande (via the Grey Glacier viewpoint), then the W highlights — the French Valley and the base of the Towers — before exiting. The John Gardner Pass (about 1,240 m) is the crux: not high by Andean standards, but fully exposed to Patagonian weather, and the descent to Grey is long and often wet. The back side between Dickson and Grey is the quietest, wildest walking — hanging glaciers, lenga forest, and a fraction of the W’s foot traffic.
When to go
The season runs roughly November to March. January and February are the most reliable months, but “reliable” is relative in Patagonia: even in midsummer you should expect four-seasons-in-a-day weather, ferocious wind, and the occasional snow flurry on the pass. December can bring surprising storms; the shoulder months are a gamble. Whatever month you choose, the wind is the defining feature — pack a genuinely storm-worthy tent and windproof layers, not the gear that survived a calm summer elsewhere.
Costs and budgeting
One detailed independent account puts the full 8-day circuit at about US$1,500 per person — covering buses from Puerto Natales, the catamaran across Lago Pehoe, campsite fees at every stop, premium tent rentals and most meals. Doing every booking yourself and carrying all your own food is the cheapest way; full-board refugio itineraries and guided trips run to about US$2,000 and up. Gear rental shops in Puerto Natales cover tents, sleeping bags and stoves if you don’t want to fly with them. Budget extra for the notorious refugio prices if the weather drives you indoors — many trekkers keep a “rainy-day fund” for exactly that.
Getting there
Puerto Natales is the gateway town: fly to Punta Arenas or Puerto Montt and continue by bus, or cross from El Calafate in Argentina. Regular buses run from Puerto Natales to the park’s Laguna Amarga entrance in season (book ahead), and a catamaran crosses Lago Pehoe between Pudeto and Paine Grande. Build buffer days at both ends — Patagonian transport and weather delay plans routinely.
Safety and practical tips
The hazards here are weather, not altitude or technicality. Check the forecast at every refugio, be prepared to lose a day to wind on the pass, and start the Gardner Pass crossing early. Streams are safe to drink untreated. Refugio shops sell snacks and basic supplies at a premium; there is no ATM in the park, so carry Chilean pesos. And book your buses in and out of the park in advance — they fill up in peak season just like the campsites.
Arjun Mehta is the pen name behind Mountains Bliss — practical mountain-travel guides with routes, costs, seasons and safety notes, researched from real trekker discussions and cross-checked before publishing. No sponsored posts, ever.
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