The center of Oslo is within easy walking distance of the dock. We used US dollars or euros wherever we went. I found the Nobel Peace Center to be disappointing for the money, but other relatives enjoyed it. The City Hall was closed to tourists while we were there. We followed the Rick Steves walking tour by the theater, past the university and royal palace, and to the National Gallery (free admission, good Scandinavian collection). The best thing about Oslo was the various squares with statues, fountains, and flowers. We walked around the Akershus Fortress (free admission), which was very interesting and had great views of the city. Food and souvenirs were extremely expensive; I paid $16 for a small troll doll. We returned to the ship to eat lunch.
Aarhus was one of my favorite ports. We walked from the ship to the cathedral (beautiful inside), the small but excellent Viking Museum in a nearby bank (look for signs), and the Church of Our Lady (interesting crypt). Then we walked along the canal, past high-fashion shops and outdoor cafes to Den Gamle By, the open-air folk museum. Den Gamle By is a must-see for anyone with the slightest interest in history. I felt like I was living in a postcard. There are workers acting out the everyday activities of the time. We saw a woman making food in the kitchen and a boy playing a harmonica and a man driving a horse and buggy, all in period costume. Den Gamle By accepts US credit cards. We had an authentic Danish lunch there. It was a long walk back for my parents in their seventies, but we could not find a taxi or a bus map. (The HAL Travel Guide was no help at all in figuring out the bus system.)
Warnemunde is an easy walk from the ship. We walked along the canal and looked at the shops. At the end of the canal is a large beach and lots of sailboats out on the water. We found a harbor cruise that took US dollars ($9 for an hour). The cruise was good for people who are interested in ports and shipbuilding or who just need a rest. For lunch we had inexpensive fish and chips and paid in euros. Two souvenir shops near the ship had German food items and nautical items, but we could not find T-shirts or fridge magnets. I found amber earrings at a shop along the canal that were a better bargain than the earrings on the ship. My US credit card was accepted.
Tallinn was within walking distance of the ship. We spent about four hours following the Rick Steves walking tour of the Old Town at a leisurely pace, stopping to shop here and there. My parents in their seventies managed the walk clear to the top of the hill. I suggest you get off the ship early because the cruise ship crowds become more intense by noon. The Nevsky Cathedral is outstanding. All shops in the Old Town seemed to take euros, but everything is overpriced. We paid in US dollars for souvenirs at some stalls set up near the ship.
St. Petersburg is by far the most amazing port. We opted to pay for two day-long shore excursions with HAL. The first one was called "The Glories of St. Petersburg." After dire warning from the cruise director about long lines to get off the ship and mean Russian passport officials, we got from our stateroom to our tour bus in just 30 minutes. The tour was operated professionally and efficiently, and our guide was excellent. Catherine's Palace was not crowded in the morning. We had a nice lunch included in the price. The Hermitage in the afternoon was more crowded, but manageable. We got some free time to look at the impressionism rooms. The Hermitage takes US dollars and credit cards. The small booths outside of Catherine's Palace took US dollars. The second day our tour was called "Imperial St. Petersburg." This was an excellent tour. We breezed through passport control the second day and went straight by bus to Peterhof Palace. It is amazing inside, but the grounds and fountains are even better. We had a delightful time and good weather. We had an included lunch on the grounds and had Russian folk singers for entertainment. Then we took a half-hour ride on a hydrofoil back to St. Petersburg and boarded the bus again. We drove by many famous sights on our way to the Church on the Spilled Blood, which is not to be missed. The inside is as fantastic as the outside. The souvenir marketplace across the street took US dollars. On this tour a couple drive-by sights were dropped from our itinerary for lack of time. We had two excellent, informative guides. There was no need at all for us to have Russian money in St. Petersburg.
Holland America provided a shuttle bus into Stockholm (roundtrip $14) to the Opera House, which is just across a bridge from Gamla Stan (Old Town). We followed the Rick Steves walking tour of Gamla Stan and spent an enjoyable few hours exploring. Here US dollars are not always accepted, but euros are. Everything is very expensive (lunch $20-$30). Try to catch the Changing of the Guard at the Palace; the band plays and it's an interesting ceremony. To avoid high prices, we returned to the ship for a late lunch.