Lac Blanc is the most photographed view in the Chamonix valley — a turquoise high-alpine lake at 2,352 metres with Mont Blanc and the main peaks of the massif reflected perfectly in its surface when the wind is still. The easiest approach is via the Flégère cable car followed by a walk of about 1.5 hours each way, climbing steadily through rocky alpine terrain. There is a refuge at the lake serving food and drinks, and it is possible to stay the night.
The walk can be extended into a loop via the Index cable car or the Col des Montets. In summer, the route is often busy by mid-morning — an early start rewards you with the best light and fewer people. The hike requires no special equipment in summer but solid footwear and layers are essential; conditions at this altitude can change quickly. The views from the lake are arguably better than from any cable car: you earn them, and you get to sit and watch Mont Blanc change colour across an unhurried afternoon.