There are two main harbours in Helsinki: West Harbour and South Harbour. You can arrive from both by tram, taxi or Uber.
From West Harbour: Take the tram nr. 7 to the stop ‘Mikonkatu’ and walk 4 minutes to Bob W, or take tram nr. 9 to the stop ‘Kaisaniemenkatu’
which is right outside Bob W. See the schedules here.
From South Harbour: Take the tram nr. 5 directly from the harbour to the stop ‘Aleksanterinkatu’ and walk 5 minutes. See the schedules here.
Alternatively, it’s about a 20-minute walk from the harbour to the building.