One of the things I like to do in Oslo is visit the various boat museums on Bygdøy. Perhaps the most famous is the Vikingskiphuset, where they have 3 of the first viking ships to be found and exhibited, but there is a collection of them.
The museums are at Bygdøy. You can either catch a ferry there from the main harbour, or catch a bus number 31 from the central station. Three of them are where the ferry lands, the vikingskiphuset is a couple of bus stops or 15 minutes walk away on the bus route back into the centre. (One stop past vikingskiphuset is the folk history museum - an outdoor museum of norwegian history, but without boats). My favourite is to take the bus to Vikingskiphuset, walk down to the point and see another museum or two, take a ferry to the main harbour and wander round there looking at boats for a bit. For a long day, have lunch in the forest or on the beach at Huk.
The Gokstad ship,
© Coralie Mercier 2006,
some rights reserved
This building contains the Gokstad, Oseberg, and Tune viking ships which were dug up in the late 19th and early 20th century. The Gokstad is, in my opinion, one of the most beautiful ships ever built, although most people say that is actually the case for the Oseberg. There are also the various things that were found with them - since they were burial ships, an interesting collection of items for daily life...
Thor Heyerdahl was a famous (or slightly mad) Norwegian anthropologist. Shortly after the end of World War II he decided to test his theory that South American people could have sailed their balsa rafts to the South Pacific, in the obvious way. He and a group of like-minded blokes went to South America, cut down a handful of balsa trees, tied them together with a bit of a platform on top, added a tiny bamboo hut and a mast, and set out for the South Pacific. Eventually they were shipwrecked, on a South Pacific island. I read the story as a boy, and it is a classic "boy's own adventure story", although it allegedly had a serious research goal. The raft is now in the museum, along with Ra II (a papyrus boat he sailed across the atlantic 20 years later, because Ra I only made it most of the way), stuff about Easter Island and his work there, and various other bits and peices as well as lots of information about Thor heyerdahl and his projects. Heyerdahl himself only died earlier this decade.
The website says "Fram is the strongest vessel in the world. This remarkable vessel has advanced further north and further south than any other vessel". It's a big claim, but true. The ship was purpose-built in the 19th century for Fritdjof Nansen, one of Norway's great polar explorers. He used it in his attempt to deliberately get trapped in the arctic ice-pack and float across the North Pole. It missed, but not by very far - the only people who had been further north were Nansen and his mate Johanssen, who had left the ship to try and ski even further north. It was also used by Amundsen when he became the first person to reach the South Pole. You can walk around on the ship, and there is a display of various related stuff as well.
I haven't been in this one for ages - never enough time. It's the first one I am going to when I get to visit Bygdøy on my own next. It's a general museum devoted to the history of doing things on and by the sea in Norway. For a country which is mostly coastline, that's a pretty big part of the history and culture...
While you're there...
There are a couple of other attractions. Between the ferry and the museums, there is a little boat standing high and dry, called the Gjøa. This is the boat that Amundsen used for teh first successful expedition to sail the NorthWest Passage. There are a handful of other interesting little boats dotted around the little harbour there. It's also not far to Huk, a nice little beach in the forest. As mentioned above, there is the Folk History Museum on the way back by bus. And little walk around Bygdøy is a pleasant way to see very nice houses or very relaxing forests.