Emerald Bay is the scenic bay on the southwest shore that contains Tahoe's only island, Fannette Island. There is a great beach on the bay with clear water and mountain views. However, you can only access it via boat or hike. The hike is not extemely long, but in involves 400-500 feet of elevation change, so some visitors might find it challenging. From the parking lot, take the paved trail to the beach.
HW 89 South West Shore http://www.parks.ca.gov/default.asp?page_id=506