During the summer season, which is roughly the end of May to mid-September, several boat companies offer a ferry service from Peniche Marina to Berlenga, the main island in the group. If you’re visiting in peak periods, it’s probably a good idea to make a reservation online The whole island is a nature reserve and home to several protected species of birds and plants. Fort of St John the Baptist: If you’re looking for photo opportunities, this is the place to come. The walkway out the the fort takes you past arches, coves and enticingly clear water with little motor boats bobbing patiently. Check out this private tour from Lisbon: https://www.viator.com/tours/Lisbon/Private-Tour-Berlenga-Grande-Island-Day-Trip-from-Lisbon/d538-6999PRTATLANTIC?pid=P00012552&uid=U00356192&mcid=58086