Ang Thong National Marine Park (no slide, 9 hrs)

Ang Thong National Marine Park is one of Thailand's most breathtaking protected areas, and Tranquilla brings you there in fitting style. This custom-built vessel stretches 72 feet and accommodates up to 60 guests, making it an ideal choice for groups seeking a shared full-day experience without sacrificing comfort or space.

The destination itself is the star. The Golden Bowl — a hidden saltwater lake cradled within the park's dramatic limestone formations — is among the most striking natural features in the Gulf of Thailand. Reaching it by sea, with the archipelago's karst islands rising around you, is the kind of journey that stays with you long after you've returned to Koh Samui.

Tranquilla's nine-hour tour gives you genuine time to absorb the park rather than merely glimpse it. A large group boat of this scale offers the stability and deck space that smaller vessels simply cannot match, letting guests move freely and settle into the pace of the day. If you're looking for a full-day XL experience in Ang Thong National Marine Park, Tranquilla is a considered and capable choice.