Kingston Water Taxi temporarily in service from Crawford Wharf (1 Brock St, downtown Kingston) to the  HMCS Cataraqui docks (24 Navy Way, Barriefield) per https://www.1000islandscruises.ca/watertaxifaq/

The same company's tour boats (Island Queen, Island Star, Island Belle) also run from Crawford Wharf - although the office (and likely the tickets) are 248 Ontario St. K7L 5P7