Will be on a cruise and spending one whole day in each of these cities...really not an excursion/organized type of person and like to wander on my own
What do I want to be sure to see in each of these places....do I need public transport in either of these or are they walkable. Thanks for any help.

They are easy to wander on your own -- we visited them both on a Celebrity about 12 years ago -- our line shuttled us to downtown Helsinki where we visited the market along the water (do not recall what day of the week it is, but you have no choice, you'll be there when you'll be there, maybe you'll luck out) which had lovely local crafts at very reasonable prices. There is a beautiful esplanade that reminded me of the Tuileries. We then wandered all over the downtown area, had lunch, and caught the shuttle back to boat at end of day. In Tallin we did the same thing, believe the old city was walled so we circled that, had lunch, browsed/shopped, it was lovely. No reason for organized tours there. Actually did the same in Oslo, Stockholm and Copenhagen too with only official tours in St.P.

Tallin - absolutely not. The ferry docks very near the old town so it is all walking. In Helsinki, as mentioned, I think you have to catch a shuttle to the centre of town but most major sights are then within walking distance.

Tallin...lovely little town. Very walkable. Head to the Upper town for great views over the red roofs of the lower town. Olde Hansa is a great authentic restaurant down in the central square...very dark inside, waiters and waitresses dressed in period costumes...very much enjoyed our meal. Would love to return to Tallin someday.

We were in Tallin for one day. Arrive at 6 a.m. and left in the late afternoon. Walking around the town is very pleasant. The architecture ranges from a medieval wall to whimsical turn of the century figures high up on rooftops:

Michael--Loved your pictures--thanks for the info on Tallin--we really like to wannder on our own so this sounds right up our alley!!

In Helsinki, the cruise ship shuttle will probably drop you off at one end of Esplanadi Park. From here you can walk to Senate Square (home to Helsinki Cathedral); Uspenski Orthodox Cathedral on the Katajanokka peninsula; the Central Train Station/Helsinki Railway Square; Old Market Hall, which is at Market Square on the waterfront (where you can catch the ferry to Suomenlinna). About Suomenlinna:
https://www.suomenlinna.fi/en/fortress/
If you'd like to see the Rock Church, it would be best to jump on a tram. The #2 or #3 tram, I think. You can check with the Tourist Information office
The Sibelius Monument is also a popular tourist attraction.
An all-day bus ticket cost € 9 and includes the ferry to Suomenlinna:
https://www.hsl.fi/en/dayticket
Most of the above attractions are on this map:
https://media-cdn.sygictraveldata.co...f?fileType=pdf

Great info and thanks for the day ticket info--sounds like a cheap way to get around by tram and ferry

Once in Tallinn, make sure to pay a visit to the oldest still running Pharmacy in Europe, there is a showcase room for old medicinal tools and drugs, very fascinating!

And slightly creepy at the same time! But I agree. It's worth the stop here. It opened in 1422, and is still in the same spot (i believe.)