The British National Maritime Museum at Greenwich certainly is one of the most important and largest maritime museums in the world. It holds a large collection of maritime art, British and Dutch paintings, cartography, navigational instruments and ship models.
There is more information about the museum and on-going events on the homepage of the Royal Museums Greenwich.
I was most impressed by the collection of paintings they displayed. It was a joy and very interesting to see these famous paintings. The original works revealed much more details than I remembered from the prints I had seen before in several books.
You can browse the fine art collections of the National Maritime Museum and buy large format prints of the paintings online. They show the prints by 600 * 350 pixels which is quite good for selecting.
In the museum we found a small but fine selection of contemporary ship models displayed. However, when we visited in 2009, there was a photography ban.