Ferry Puerto Montt Puerto Natales
Some hikers list the multi-day ferry trip between Puerto Montt & Puerto Natales as one of the highlights of Patagonia. <Navimag ferry website>
But many more feel it is long & overpriced for what you get. For about the same cost as the cheapest berth you could fly, saving those days for hiking.
On the other hand, the ferry is a great way to meet others to hike Paine as you will all be on the same hiking schedule.
The ferry travels only once a week in each direction so timing transport can be problematic.
Food is nothing special at any fare class. Bring your own water on to the ship to be safe.
Highlights include scenic fjords & inaccessible glaciers. You might see whales, dolphins, seals &, rarely, killer whales.
Bus
In an empty, flat land like eastern Patagonia in Argentina, the bus is the easiest way to get around. Service is good but not inexpensive by South American standards.
Unfortunately the shortest route to Paine, Argentina Highway 40, is so bad & remote that major bus companies do not offer that service they take the long way around via Rio Gallegos. If you really must take Highway 40, an expensive backpacker van might take you.
Bus El Calafate <> Puerto Natales
The majority of Paine hikers also travel to El Calafate, Argentina where they visit fabulous Moreno Glacier <photos> & perhaps hike Fitz Roy.
It could not be easier to arrange a bus El Calafate <> Puerto Natales. Many bus companies offer fairly equivalent service. (Check if the bathroom door is locked / out-of-service, a typical problem, it seems.)
Border crossing between Chile & Argentina on this route is relatively hassle-free.
Bus Puerto Natales <> Punta Arenas