Start with a classic bowl of pho in the Old Quarter; quick, local and a great introduction to Vietnamese flavours. Check vendor opening hours (typically early morning until late).
Check-in for a day/overnight cruise — enjoy a seafood lunch while the boat sails among limestone karsts; boarding times vary so confirm with operator.
Explore a cave like Sung Sot or Ti Top and optional kayaking in a calmer bay area; excursions run in the afternoon—check cruise itinerary for exact timing.
Transfer back to Hanoi (approx 3.5–4h) and head to Noi Bai Airport for an afternoon flight to Dong Hoi (travel times tight—plan flights with cushion).
Visit Paradise Cave with spectacular stalactites and large caverns; site open daily (usually 8:00am–5:00pm) — allow 1.5–2 hours for walking and photography.
Wander the lantern-lit streets, visit assembly halls and small museums — the town is open broadly from early morning until late but specific museum hours vary; buy entry tickets if visiting monuments.
Visit the Cham temple complex at My Son—open roughly 6:30am–5:30pm; allow 4–5 hours including travel from Hoi An. Book with a guided tour or private car.
Early departure for a full-day tour of the Mekong—travel time is about 1.5–2.5 hours depending on the chosen town; confirm tour itinerary and pickup time.
Have a last meal and leave for Tan Son Nhat Airport in good time—allow at least 2–3 hours for international flights (check your airline’s recommended arrival time).