Distribution and abundance of Pyrodinium bahamense cyst in the harmful algal blooms risk waters in Indonesia. Pyrodinium bahamenseas Harmful Algal Blooms (HABs) is one of the rising environmental problems in the coastal areas of Southeast Asia, particularly in Indonesia. Cyst bank formed after the blooms of P. bahamense is a potential source for the future blooming events. Therefore, an effort to describe the distribution and abundance of P. bahamense cyst banks in Indonesian coastal waters is necessary as a part of the mitigation strategy against the negative impacts of those toxic dinoflagellate blooms. This study was done as a desk study, which included a literature study, reanalysed of previous research data, and reanalysed of preserved samples or stored raw samples. Data and samples used in this study were collected and analysed from part of past researches in Lampung Bay, Jakarta Bay, Cirebon coastal waters, and Ambon Bay. This study also included an analysis to determine the P. Bahamense HABs risk level in the studied areas based on the cyst density and distribution data. Results showed a low density of P. bahamense cyst in Lampung Bay and Jakarta Bay, with cyst density \textless50 cysts.g-1 wet sediment. In contrast, the bottom sediments of Ambon Bay and Cirebon coastal waters contained high cyst density, which reached \textgreater1,000 cysts.g-1 wet sediment. Based on those data, the P. Bahamense HABs risk in Jakarta Bay and Lampung Bay would be generally much lower compared to Ambon Bay and Cirebon waters. The existence of cyst banks in those coastal waters may indicate  a possibility of future blooms of P. bahamense.