Lago Yarinacocha is the reason most travellers come to Pucallpa. It's a long, sinuous oxbow lake — about 20 kilometres end to end — left behind when the Ucayali River cut a new course. The water is calm, brown, and home to two species of freshwater dolphin: the pink Amazonian boto and the smaller grey tucuxi, both regularly seen in early morning and late afternoon.
The starting point for boat trips is Puerto Callao, on the lake's southern shore and a 20-minute mototaxi ride from central Pucallpa. The standard half-day trip takes in two or three Shipibo communities, a stretch of flooded forest for dolphin-watching, and a stop for lunch at one of the lakeside restaurants. Negotiate with the boatmen on the malecón; expect to pay 80–150 soles for a private launch for two to four people. Sunset on the lake, with parakeets coming in to roost in the trees, is the single best thing you can do in Pucallpa.