Thiruvananthapuram's hills make it less walkable than it looks on a map. Auto-rickshaws are the standard way to get around and are metered (insist on the meter or agree on a price first). App-based rickshaw services are also available. The central museum compound, Palayam, and the fort district can be connected on foot if you are willing to navigate the slopes; from the museum area to the fort is about 3 km.
Local city buses are cheap and run throughout the city, though routes can be confusing for newcomers. For Kovalam and the beaches south of the city, auto-rickshaws are expensive for the distance; a taxi or app-cab is more practical. To reach Shankumugham Beach near the airport, a 20-minute auto ride from the centre is the standard option.