Green Lake Trek , the base camp of Mount Khanchendzonga on the Zemu Galcier in North Sikkim is a splendid walk with the variety of flowers like rhododendrons, blue poppies and primulas all in bloom. The mountain views are fantastic with amphitheater of peaks with Khangchendzonga at the head of the valley. However, the Green lakes base camp is more than 5000 metres and so proper acclimatization is essential to avoid altitude sickness.