Sikkim is a mountainous state located in Northeast India. It is known for its scenic waterfalls and biodiversity. The document discusses Sikkim's geography, noting that the state is primarily mountainous with lush vegetation and many perennial waterfalls. It also highlights the state's notable peaks like Kangchendzonga, the third highest mountain in the world. Finally, it describes Sikkim's rich biodiversity, including over 4000 plant varieties and 700 butterfly species, many of which are endangered.