Dolphin Watching in Nepal| Sapta Koshi River|

October to June is the recommended season for the Sapta Koshi dolphin safari, covering autumn, winter and spring; the Gangetic dolphin is present year-round but water levels and clarity vary significantly with the monsoon. October and November give low, clear water after the rains, the best boat access to the upper river channels and peak bird diversity as migratory species arrive at Koshi Tappu.

Winter months (December to February) are cool and dry, with excellent visibility on the water and some of the highest wading-bird concentrations of the year. Spring (March to May) is warm and the river rises gradually; dolphin sightings remain good. The monsoon (June to August) brings high, fast, murky water that makes dolphin spotting and navigation harder, and some lodge access routes flood. The season cards below show the month-by-month picture.

Koshi Tappu Wildlife Reserve requires an entry permit for all visitors; the current fee is NPR 1,000 per person per day for international tourists, paid at the reserve entrance. Swotah includes this permit in the trip cost and arranges it for you. No separate national park permit is required for the Sapta Koshi boat sections outside the reserve boundary.

Nepal visa is available on arrival at Kathmandu's Tribhuvan International Airport for most nationalities: bring a passport valid for at least six months, one passport photo and the fee in US dollars cash. The domestic flight to Biratnagar requires a valid photo ID, and Swotah handles the booking. No restricted-area permit is needed for this itinerary.

Accommodation at the reserve is a riverside lodge or eco-resort within driving distance of the Koshi Tappu Wildlife Reserve boundary, with private rooms, hot water and electricity. The lodges in this area are comfortable rather than luxury, in keeping with the remote riverine setting, and most have open-air dining areas overlooking the flood plain.

In Kathmandu, the tour uses a standard 3-star hotel with private bathrooms, Wi-Fi and breakfast included. Rooms at the reserve are booked in advance to secure availability during peak autumn and spring seasons. Upgrades to higher-category lodges are possible on request when availability allows.

Food at the reserve lodge is full board: breakfast, lunch and dinner are included, with a mix of Nepali dal bhat (lentils, rice and vegetables), local river fish dishes and simple international options. The lodge cooks use fresh vegetables from the floodplain market and, when the fishermen's cultural programme runs on day 5, the evening features a riverside fish meal prepared by the local fishing community.

Drinking water at the lodge is supplied as boiled or treated water; bring a reusable bottle to refill rather than buying single-use plastic. In Kathmandu, bottled water is widely available. Carry water purification tablets as a backup during the boat days. Tell Swotah in advance about any dietary requirements or allergies.

The Sapta Koshi reserve sits in the eastern Terai about 25 km south of Biratnagar, Nepal's second city, which is served by daily domestic flights from Kathmandu's Tribhuvan Airport on Yeti Airlines and Buddha Air; the flight takes about 40 minutes. A private vehicle then drives you south from Biratnagar airport to the lodge near Koshi Tappu, a journey of roughly 45 to 60 minutes on the East-West Highway and local roads.

On the return leg, the same route runs in reverse: drive to Biratnagar, fly back to Kathmandu. Road access to the reserve can be affected by seasonal flooding in the monsoon; Swotah monitors conditions and adjusts logistics if needed. The boat rafting on days 3 and 4 launches from the river bank near the lodge.

The Gangetic dolphin (Platanista gangetica) is one of only six species of freshwater dolphin in the world and is listed as Endangered on the IUCN Red List. It is functionally blind: its eyes lack a lens and can detect only light direction, so it relies entirely on echolocation to navigate and hunt fish in the turbid water of large South Asian river systems. The Koshi system, draining the combined flow of seven tributaries from the Himalaya, provides the deep, braided channels and fish stock the species needs.

On the water, the susu announces itself with an audible exhalation as it surfaces to breathe, which it must do every 30 to 120 seconds. Sightings typically show the curved back and small triangular dorsal fin breaking the surface for a second or two before the animal dives again. The Sapta Koshi population is estimated at approximately 30 to 40 individuals, though this figure is based on survey data that is periodically revised. Swotah's guides know the river sections where the dolphins concentrate and time the boat run to maximise sighting opportunities.

Koshi Tappu Wildlife Reserve covers 175 square kilometres on both banks of the Sapta Koshi in Sunsari and Saptari districts and was declared a Ramsar Wetland of International Importance in 1987. It was established in 1976 primarily to protect the last surviving population of wild water buffalo (Bubalus arnee) in Nepal; the reserve now holds roughly 400 wild buffalo along with hog deer, spotted deer, blue bull (nilgai), smooth-coated otter, jackal and a small population of gharial crocodile in the river channels.

The birdlife is the reserve's other headline figure: 485 recorded species, including 114 water-bird species, make Koshi Tappu one of the top birding sites in South Asia. Migratory species swell the count each winter, with large flocks of bar-headed geese, teals, pochards and waders concentrated on the open sandbars and backwaters. The reserve headquarters visit on day 2 gives context on the conservation programme before the boat days begin.

Mobile connectivity near the Koshi Tappu reserve is serviceable but not fast: Nepal Telecom (NTC) and Ncell both cover the Sunsari district with 3G and patchy 4G, enough for messaging and maps but not reliable for video calls. Swotah provides a tourist SIM card that works across the trip.

The lodge near the reserve has mains electricity and sockets for charging phones and cameras; a power bank is still worth carrying for the full boat days when you will be away from the lodge for several hours. In Kathmandu the hotels have reliable Wi-Fi and power. A universal travel adapter covers Nepal's mix of Type C, D and M sockets.

Responsible travel in and around Koshi Tappu means following your guide's instructions at all times on the water and inside the reserve, staying a safe distance from wild buffalo and not approaching dolphins with a motor (the boat uses paddles or poles near the animals), and carrying out all waste from the river islands. Koshi Tappu's wildlife is under pressure from sand mining, poaching and invasive vegetation, and low-impact tourism is one of the arguments for keeping the reserve funded and staffed.

Tipping is customary and meaningful for the seasonal staff who run the safari: a common guideline is 10 to 15% of the trip cost, distributed among your guide, driver, boat crew and lodge staff. The fishermen who host the day-5 cultural event also appreciate a direct tip for their time. Booking with a registered operator like Swotah ensures that reserve permits, staff insurance and boat safety are handled properly.