As a region famous for its coastal beauty, North Sulawesi delivers underwater charm that attracts tourists, both domestic and international. It has a beautiful natural charm, especially on the northern mainland of Sulawesi Island. Underwater tourism has been famous since the 1990s. The biodiversity of Bunaken, Siladen, and the Valley Strait, with its diverse endemic marine biosphere, is able to make North Sulawesi an underwater paradise for divers. By presenting information from the seven most popular diving destinations, this book is expected to be a useful reference, not only for tourists, but also for the public, governments, and tourists in the efforts to preserve and develop the potential of marine tourism in Northern Sulawesi. We thank all those who have contributed to the preparation of this book. May the One God always give blessing and smoothness to all of us in our efforts to build a better North Sulawesi