One of the best ways to see Stockholm is by water, and the best way to see many of Stockholm's sites is by taking one of the many boat tours offered by many boat/tour operators.
Among these is the "Under The Bridges of Stockholm" tour, offered by Stockholm Sightseeing. It is a two hour boat tour that travels the waterways between the 14 (or so) islands that Stockholm is built on. The tour illustrates how essential the nearly 60 bridges that connect these islands are for the purpose of land travel around Stockholm by car, bus, and train.
This tour passes under fifteen bridges and through two sets of locks to manage the different water levels between Lake Malaren and the Baltic Sea. The tour starts and ends in downtown Stockholm on the docks in front of the Grand Hotel.
After backing away from the dock and leaving downtown, in approximate order, we passed the Royal Palace, the National Museum, Stockholm City Hall, Vasa Museum, and the Grona lunds tivoli amusement park, in addition to countless beautiful landscapes. There is an audio recording played through headphones that is synchronized with the tour that points out all the points of interest. The audio recording is available in many languages.
It is important to note that although the tour includes a lot of sites, that it does not stop at any of them. You need to look and take pictures on the go. It is an excellent introduction and perspective to Stockholm, its sights, bridges and locks. It serves as a basis for you to decide which of the sites you want to go visit on foot and tour individually at length.
Tours leave from downtown Stockholm at the docks in front of the Grand Hotel. During the summer there are many tours scheduled. When you arrive, there is a good chance that one tour or another will be leaving soon. Stockholm Sightseeing has tours leaving every half hour....one tour leaves every hour on the hour, and a different tour leaves every hour at half-past. Buy your ticket in the ticket booth at the departure point.
In addition to the seeing the sites, this tour provided me a new perspective on Stockholm. I have visited Stockholm many times, and visited many of the sights by foot (in other journal entries), and can say that the tour is well worth the 140 SEK ($14 US) price of admission.
To get to the docks, take the subway (Tunnelbana or T-Bana) to Kungstradgarden, exit the station and walk toward the water. After my tour, I walked back toward the Kungstradgarden (Kings Garden) subway station and right into the Restaurant Days at Kings Garden festivities.