There are a variety of boat cruises available on the lake. Most operate out of the South Lake Tahoe Area, but there are tours available from Tahoe City as well. There are day tours to Emerald Bay and sunset dinner cruises as well.
North Tahoe Cruises have their office on North Shore Blvd. in the middle of Tahoe City at the Lighthouse Mall. Their boat is styled as a steamboat and called the Tahoe Gal.
For the more adventurous, there are also sailboat tours of the Lake. These depart from the Tahoe City Marina. The organization is Tahoe Sailing Charters.