Leaving Kathmandu's northern suburbs, the day climbs steadily out of the valley past Dhulikhel to a high point of around 1,580m near Namobuddha, one of the valley's most revered Buddhist pilgrimage sites, before a long 2,000m+ descent drops through pine forest and farming villages into the warm Sun Koshi valley. A relatively gentle opener — one big climb, one big descent — that sets the tone for the hill country ahead.

The leg's toughest rollercoaster day, rarely flat for more than a few hundred metres as the road threads along Nepal's Mid-Hill Highway through Sindhuli district, past terraced hillsides, stone-and-tin villages and constant ridgeline views, before a sustained final climb to Mahadevsthan (~1,510m). Road surface is the thing to watch — sections of this highway remain unsurfaced gravel or rough patched tarmac, and the very stretch we ride (Khurkot–Ghurmi) was landslide-blocked as recently as late October 2025. Physically, this is the hardest day of the whole leg

The longest day by distance, starting with more of Day 2's undulating hill riding before committing to a long, sustained drop off the escarpment into Nepal's flat Terai plains, with jungle and terracing giving way to rice paddies and market bustle as the heat and humidity climb. It finishes at Itahari, a crossroads town near the Koshi River system, on good fast tarmac for the final flat stretch.

A gentler, flatter day across Nepal's eastern Terai that also delivers the leg's first border crossing — the open land border at Kakarbhitta/Panitanki, a proper slice of subcontinental market chaos. From there the route continues on generally good tarmac through North Bengal farmland to Siliguri, gateway to the eastern Himalaya, with traffic noticeably busier on the Indian side.

The flattest, fastest day of the leg, rolling east through the Dooars — West Bengal's tea-garden and forest belt, with elephant corridors and broad rivers draining down from Bhutan — on good national-highway tarmac. It finishes at the India–Bhutan border, where Jaigaon's bustle gives way in a single step to the order of Phuentsholing, a fitting easy day before the leg's biggest test.

Leg 16's queen stage: a single, sustained climb of over 4,000m through dense Bhutanese forest, past the Chukha hydropower dam and up to Chuzom, where three chortens mark the confluence of the Wang Chhu and Paro Chhu rivers, before a tough, dramatic finale into Thimphu at ~2,320m.