Swami Satyananda was a teenager, a little boy, when he came to the Ashram, but very active and proficient in Hatha Yoga right from the beginning. Many were the departments of the Ashram in which he rendered service, particularly during the later days in the Hindi department of the Ashram. He edited the Hindi journal and wrote articles and was proficient even in composing poems in Hindi and Sanskrit, language; very active and tireless in his service. One of the great contributions of his, which is to be remembered for all times, is the hard work that he did in bringing about a translation and commentary in the English language of the Brihadaranyaka Upanishad by Sri Gurudev. He was actively connected with this work and, but for his struggle day and night in seeing to it that the manuscript was made ready, the book would not have actually come out. He was solely responsible, one may say, for the coming out of this book—the commentary on the Brihadaranyaka Upanishad of Sri Gurudev. Later on, he left the Ashram on an inner feeling of establishing himself separately in a secluded place and he found himself somehow landed in Bihar, a place called Munger, where devotees somehow recognised some value and worth and intrinsic merit in him, collaborated with him and the result was a very magnificent well-planned Institution of Yoga teaching, which became the venue for imparting instructions not only to hundreds of seekers in India, but also countless seekers came from the West, many of whom took Sannyasa, under Swami Satyananda. He did such active and intensive work in the field of Yoga that his name is known in many places even in the West as a very competent and effective teacher of Yoga and the way of spirituality. Now he has taken Mahasamadhi.
Swamiji established The Sivananda Yoga tradition having his mission spread all over the world.
His work on Yoga and Tantra basically Kundalini Tantra,Yoga Nidra,Meditation was very much admirable.
Swami Satyananda's Website