Helsinki via Cruise Ship - Transportation Suggestions

Not a lot of people on this forum take cruises so I suggest you take your query to cruisecritic.com. You can get info there on any cruise port ( almost) in the world and there is a forum where you can ask questions and know you will get answers from knowledgeable people.

There are many people on this forum that are very experienced cruisers. And the Baltic cruises are one of the best cruises in the world--visiting incredible cities, including our favorite, St. Petersburg. Cruises are by far the most affordable way to explore the region as Scandinavia is deadly expensive.
Hop on Hop off buses will be waiting at your ships' docks, and it's the best way to see Helsinki. The center city is not particularly large so the circle they make doesn't take very long to get around. We did stop at a church built into a large rock, a great museum and the shopping district downtown. Both the red and green buses are comparable as they stop basically at the same places.
We found Helsinki to be a very clean, nice town. I just hope the early May weather is good for you as that's kind of early in their tourist season.

Which harbor does the Regal Princess dock? The Market Square is at the head of South Harbor very close to Helsinki Cathedral. (The Cathedral is about two short blocks inland from the Market Square). The Viking Ship Line is on the east and the Sija Line is on the west. Both the Viking Katajanokka Terminal and the Sijia Olympiaterminaali Terminals are about a 10 minute walk to the Market with the Sijia Terminal being a bit father than the Viking.

Helsinki is very walkable unless you are loaded down with luggage and gear.

However, if your ship docks at a West Harbor quay, it would be a pretty long walk (3 km?)
http://www.cruisemapper.com/ports/helsinki-port-49

West Harbour: There are two quays fro cruise ships – Valtameri Quay and
Melkki Quay. Both are located at the south end of Helsinki cruise port
West dock. The distance to the center of Helsinki is about two miles
and there are shuttle services. You can also catch a taxi or a ferry
to the Market Square (Kauppatori).

South Harbour: Helsinki cruise port has two quays at its largest dock –
Pakkahuone Quay and Olympia Quay. It is located in Helsinki downtown
and all attractions are in easy walking distance.

RE: I just hope the early May weather is good for you as that's kind of early in their tourist season.
On our first trip to Finland we arrived in Helsinki early April in the middle of a snow storm and frozen harbors and departed late April with green lawns, sidewalk cafes, Finns walking through parks with Nordic poles and in general sunny spring weather. However, the Baltic still had enough ice that the hydrofoils to Estonia were not running.
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Thank you all very much for your replies. We decided to see this region on a Baltic cruise as I have always wanted to go to St. Petersburg and, as David pointed out, this is such an expensive region in which to travel. We are traveling in early May with the hope of avoiding the heaviest tourist season that comes in the summer months and we do expect cold weather. Edgar, thank you for the hope of Spring weather. Thank you as well for your information on the ports and transportation options into the city. That information is exactly what I was hoping for and now I feel like we will be prepared to see everything and have a lovely experience in Helsinki. If you have any other insight to add, please share it. I appreciate all of your help and David's as well. Thanks again.

Finnish Met short term (one to three day) forecast were amazingly accurate during our visit this past February. Here's their seasonal climate commentary:
http://en.ilmatieteenlaitos.fi/seasons-in-finland

In spring, the mean daily temperature rises from 0°C to 10°C. Spring
begins in early April in Åland and the southwestern archipelago and
later in April elsewhere, except for northernmost Lapland, where it
does not begin until early May. Thus, spring begins a month earlier in
the south than in the north. Its duration ranges from 45 to 65 days,
being longest in the maritime islands and coastal regions, because of
the coolness of the sea. Once the mean daily temperature exceeds 5°C,
the thermal growing season is considered to have begun. This takes
place about one month after the beginning of spring: at the end of
April in southern Finland and at the end of May in northernmost
Lapland.

PS A way to interpret Celsius temperatures in human terms is as follows:
Negative Celsius temperatures = Very Cold
Single digit (>0 = 10 <20) = Cool
Mid-Twenties = Comfortable
Mid-Thirties = Warm to Hot
Forties = Hot to Very Hot

How long will your ship dock in Helsinki? If you've got most of the day, you should have no trouble. Neither harbor is very far from the center of town, as both are near to easy tram lines (and taxis, too, I would think. I don't remember). I took the tram to both harbors over the course of my trip, but only because I had my heavy backpack with me. Otherwise it would have been a pleasant walk.

Caroline