People living in the archipelagos get around locally with the ubiquitous banana boat, a 30-40 ft fiberglass hull with an outboard motor.
Also, two or three shipping lines also sell tickets for passengers who want to leapfrog from one city to another. These ferries run only two or three times per week and offer upper and lower class. Upper gets you a bunk to sleep on while lower gets you a hard seat.
There is a ferry twice a week between Madang and Wewak.
One small ship leaves the city of Lae once a week, stopping at Finschhafen and Umboi Island. Sleeping on the open deck of a ship as it crawls slowly through the South Pacific night is about as romantic as it sounds, but beware - it gets cold on the open ocean no matter where you are, so take some warm clothes or buy a cabin inside.
By Public Motor Vehicles (Pmv)
The most common way to travel is by PMV/bus with the locals.
Lae, Madang, Goroka, Tari, and Mount Hagen are all connected by a good highway. As a newcomer it is probably advisable to get help from locals e.g., hotel-staff. Most towns have several starting points. A trip from Lae to Madang costs around 20 Kina, to Mt. Hagen 30 Kina.
Papua New Guinea has historically been one of the world centers for aviation and still features some of the most spectacular flying in the world. In the 1920s, Lae was the busiest airport in the world - it was there that aviators in the gold mining industry first proved that it was commercially feasible to ship cargo and not just people by air. In fact, Lae was where Amelia Earhart set off on her last journey.
Air transport is still the most common way to get around between major urban centers - indeed, pretty much every major settlement is built around an airstrip. In fact, the main drag of Mt. Hagen is the old airstrip! Travel from the coast into the Highlands is particularly spectacular don't take your eyes off the window for a second! and pilots from Australia, New Zealand, America and other countries work here just for the great flying experience. If you do not like like small planes or even smaller helicopters however, flying to more remote locations here may not be the best option for you.
The two major domestic airlines are Air Niugini and Airlines PNG:
Air Niuginiconnects Port Moresby and, to a lesser extent, Lae with most of the provincial capitals, but does not offer much of a service between the smaller towns. A domestic route map is available at (http://www.airniugini.com...). The airline flies Fokker F100s as well as smaller propellor planes.
Airlines PNGconnects a large number of smaller centers. Planes with a seating capacity from 20 to 36. It operates on the mainland and does not serve the main outer islands. A route map is available at (http://www.apng.com/index...).
Papua New Guinea is a strange place when it comes to travel. The tropical conditions, fierce geography, and lack of government capacity means there are very few paved roads in the country.
With the exception of a brief span of road connecting it to the immediate hinterland and a road that will enable you to follow the coast southeast for a few hours, there are no major roads linking Port Moresby to anywhere else.
On the north coast, a tenuous highway runs from Madang to Wewak only in theory.
The big exception to this is the Highlands Highway, which begins in Lae the country's main port and runs up into the highlands through Goroka to Mt. Hagen with a fork going back to the coast and Madang. Shortly outside Mt. Hagen the road branches, with southern line going through the Southern Highlands to Tari while the northern line runs through Enga province and ends in Porgera.