Distance: 2.5 miles (4 km) loop around the lake
Trailhead Elevation: 8,150 feet (2,480 meters)
Elevation Gain: none
Although there's technically no trail along Tenaya Lake's northern shore, where the Tioga Road runs, the shoulder is wide (a rarity on the Tioga Road) and you should be able to walk safely along this shore to complete your loop. Do watch for traffic, though; visitors will be driving at a leisurely pace (it's a 25 MPH zone) but can hardly help being distracted by the scenery here.
There are beaches along the eastern and western ends of the lake. The eastern one seems to be more popular with sunbathers, possibly because they get more afternoon sun and possibly because mosquitoes, in my experience, are more likely to be found on the western beach. The western beach is where you'll find the fabulous postcard views, though.
Polly Dome, along the lake's northeast shore, is popular with rock climbers. On most summer days you can spot a few people ascending the dome and several more at the base watching them.