Whale-watching vessels have become valuable platforms for cetacean data collection worldwide. In the Azores, a cetacean hotspot in the Atlantic, Futurismo Azores Adventures, a family-owned tourism company with whale-watching as its core business, has been collecting data regularly since 2008. The current dataset compiles observations of 20 cetacean species and 19 other species of marine megafauna, recorded by Futurismo Azores Adventures off São Miguel Island (Azores, Portugal) from 2008 to 2018. Data was collected during 4219 whale-watching commercial trips conducted daily and year-round. This information has been prepared for publication within the framework of the DTO-BioFlow project, which aims to enable a data flow into the EU Digital Twin Ocean.