The Yumthang or Sikkim Valley of Flowers is a NATURE SANCTURY, on the way to go there you can see river, the mountains behind the mountains, so many waterfalls (literally) coming from white rocks, lush forested landscapes, pasture land on rolling meadows surrounded by the Himalaya, hot springs and yaks in North Sikkim.
Yumthang Valley is about 25 kms from Lachung located at an altitude of 12K feet and this takes around one and half an hour drive from there. Yumthang is the home of Shingba Rhododendron Sanctuary, which has 24 species of the rhododendron, the Sikkim’s state flower. The flowering season is from late February to mid June, when millions of flowers bloom the carpet of valley. Actually, we couldn't see a valley full of flowers because we visited there in November. But in whichever season you visited there, you will miss something.
And Further up about 23 kms (another 1.5 hour drive, while the road is quite bumpy, but the reward is awesome) from Yumthang at an altitude of 14,540 feet is the Yumesamdong, which is commonly known as Zero Point. This is place, where the civilian road ends and you can't drive further because a short distance away from here is the China border. There is nothing after this area and therefore this place's name is Zero Point. So what do you expect at Zero Point? Yumesamdong is the place where three rivers meet with surrounding snow-clad mountains and offers amazing scenic views. This area remains snow covered for most part of the year. At Zero Point you will find some stalls (see pictures) where locals sell maggie, chana masala, boiled eggs, tea-coffee and alcoholic drinks.
On the way back after visiting Yumthang Valley and Zero Points, you can visit Yumthang Hot Spring. Before the valley, a pedestrian pathway goes over a small bridge and reaches this Hot Spring. You can see here, two hot springs. Surrounded by snow all around, this surprisingly natural warm water comes as a pleasant surprise. This is sulfur rich water and said to have medicinal value. The big hot spring is covered (see pictures) by small hut.