Silversea Cruises, announcing its 2004 itineraries, will make its first-ever visit to Alaska next summer. The 28,000-ton, 388-passenger Silver Shadow will offer 11 Alaska cruises, whose itineraries may also include inaugural calls in Seattle and Vancouver. The cruises will vary in length from seven to 14 days. In other port-firsts, pathfinder Silver Shadow will call at 10 new-for-Silversea cities in Japan. These include Kobe, Tokyo, Nagasaki, Sapporo, Hakodate, Kanazawa, Sakaiminato, Moji and Shimonoseki. Itineraries on these springtime voyages, which will range from nine to 14 days, may also include stops in Russia and China.