Gun Hill is Mussoorie’s second-highest point reached by a short cable car or walk — panoramic Himalayan and Doon Valley views. (Cable car generally 9:30am–5:00pm).
Kainchi Dham is a well-known Sai Baba ashram/temple — peaceful for darshan and a short aarti visit. Temple timings are usually from early morning till evening (approx. 5:00am–8:00pm); check for special aarti timings.
Visit the Naina Devi temple on the lakeshore and take a 30–45 minute row/engine boat on Naini Lake for scenic views. Temple open long hours; boating typically 8:00am–6:00pm.
Long drive back to Dehradun airport (approx. 6–7 hrs depending on route and traffic). Start early to reach for an afternoon flight; plan short breaks en route.