This question has been asked and answered many many times in great detail. To view earlier replies simply type petersburg into the keyword section of the 'Find a Question' box (highlighted in blue). In here you will find many responses and I think the one to portergill of Bristol with 20 replies, should answer your question (to which I think you will find the answer to be a resounding NO!).
No, No, No not on your own. Go with a local tour company or the ship's excursions. ... Neil.
Princess Cruises - Crown Princess - 4 Apr 2017 - 5nts
Rome (Civitavecchia) : Kotor : Corfu : Rome (Civitavecchia)
Now from £489pp
View No Fly Cruises from Southampton >>
Click here to see offer
Princess - Pacific Princess - 26 February 2017 - 22nts
UK : Hong Kong : Sanya : Singapore : Phuket : Cochin : Mumbai : Dubai : UK
Now from £1699pp
Click to View Info Page>>
Princess - Pacific Princess - 07 February 2017 - 24nts
UK : Sydney : Papua New Guinea : Yap : Koahsiung : Hong Kong : UK
Now from £1999pp
Click Here To View More Princess Cruise Deals >>