Boat Tour in The Osa Peninsula Found: 2 | Change Filter Options Dolphin and Whale Spotting on Golfo Dulce Explore the four tropical fjords of Golfo Dulce and spot dolphins, whales, sea turtles and more. Join us for a boat ride and snorkeling adventure! Rio Sierpe Mangrove Tour Explore the tranquil Rio Sierpe River mangroves, witness crocodiles and myriad bird species, and support the cooperative's efforts to preserve over 4,000 hectares of primary rainforest.