The Essence of the Ocean of Attainments (dngos grub kyi rgya mtsho'i snying po) is a commentary on the creation stage of the Secret Union Tantra (Guhyasamaja Tantra) written by the illustrious First Panchen Lama, Blo bZang Chos Kyi rGyal mTshan (1570-1662). The practices of the Secret Union, one of the earliest higher Tantras, along with its remarkable hermeneutic system, were later applied to other Tantras as well. Still very much a living tradition, in our times the 14th Dalai Lama confers its empowerment almost every year. In this work, the Panchen Lama not only elucidates each step of the meditation in the sadhana sequence, but also offers general insights into the practice and its workings. Included is an introduction surveying the creation stage as presented by the founding fathers of the Geluk school and analyzing the contents of The Essence of the Ocean of Attainments. The translation features both explanatory annotations for the general reader and copious bibliographical endnotes for scholars. Published by American Institute of Buddhist Studies (AIBS)