I'd like to preface my review by saying I'm a marine conservation expert and well aware of what to look out for.
My partner and I partook in a dolphin-watching tour with Anthia in August 2023. The guide, Francisco Novais, was highly knowledgeable and passionate about marine biodiversity. He was super well prepared and caring with everyone on board, including children.
The tour was comprehensive - we saw common and bottlenose dolphins in close proximity and the main attractions of the natural park. It never felt too touristic or exploitative of nature, and we stopped twice to pick up plastic litter surfacing around the dolphins.
I would 100% recommend Anthia services to anyone looking for a tour in Sesimbra and will return for the diving experience in the future.